A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

        1 2 | Last   [Sort alphabetically]   [Restore default list]

  Subjects -> ELECTRONICS (Total: 207 journals)
Showing 1 - 200 of 277 Journals sorted by number of followers
IEEE Transactions on Aerospace and Electronic Systems     Hybrid Journal   (Followers: 313)
Control Systems     Hybrid Journal   (Followers: 253)
IEEE Transactions on Geoscience and Remote Sensing     Hybrid Journal   (Followers: 201)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 197)
Electronics     Open Access   (Followers: 138)
Advances in Electronics     Open Access   (Followers: 133)
Electronic Design     Partially Free   (Followers: 129)
Electronics For You     Partially Free   (Followers: 128)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 120)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 91)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 89)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 88)
IEEE Transactions on Software Engineering     Hybrid Journal   (Followers: 84)
IEEE Transactions on Industrial Electronics     Hybrid Journal   (Followers: 84)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 81)
IET Power Electronics     Open Access   (Followers: 70)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 67)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 63)
IEEE Embedded Systems Letters     Hybrid Journal   (Followers: 62)
IEEE Transactions on Industry Applications     Hybrid Journal   (Followers: 58)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 53)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 53)
Advances in Power Electronics     Open Access   (Followers: 49)
IEEE Nanotechnology Magazine     Hybrid Journal   (Followers: 45)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 45)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 41)
IEEE Transactions on Biomedical Engineering     Hybrid Journal   (Followers: 35)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 34)
IET Microwaves, Antennas & Propagation     Open Access   (Followers: 34)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 32)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 30)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 28)
Electronics Letters     Open Access   (Followers: 28)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 27)
Microelectronics and Solid State Electronics     Open Access   (Followers: 27)
International Journal of Power Electronics     Hybrid Journal   (Followers: 24)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 24)
Journal of Sensors     Open Access   (Followers: 23)
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 22)
IEEE Reviews in Biomedical Engineering     Hybrid Journal   (Followers: 20)
IEEE/OSA Journal of Optical Communications and Networking     Hybrid Journal   (Followers: 19)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 18)
Journal of Artificial Intelligence     Open Access   (Followers: 18)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 17)
IET Wireless Sensor Systems     Open Access   (Followers: 17)
Circuits and Systems     Open Access   (Followers: 16)
Archives of Electrical Engineering     Open Access   (Followers: 15)
International Journal of Control     Hybrid Journal   (Followers: 14)
IEEE Transactions on Signal and Information Processing over Networks     Hybrid Journal   (Followers: 14)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 14)
IEEE Women in Engineering Magazine     Hybrid Journal   (Followers: 13)
Advances in Microelectronic Engineering     Open Access   (Followers: 13)
IEEE Solid-State Circuits Magazine     Hybrid Journal   (Followers: 13)
Machine Learning with Applications     Full-text available via subscription   (Followers: 12)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Broadcasting     Hybrid Journal   (Followers: 12)
IEEE Transactions on Learning Technologies     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 11)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 11)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 11)
International Journal of Advanced Electronics and Communication Systems     Open Access   (Followers: 11)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 11)
Open Journal of Antennas and Propagation     Open Access   (Followers: 10)
Solid-State Electronics     Hybrid Journal   (Followers: 10)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 10)
IETE Journal of Research     Open Access   (Followers: 10)
Batteries     Open Access   (Followers: 9)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 9)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 9)
IETE Technical Review     Open Access   (Followers: 9)
Nature Electronics     Hybrid Journal   (Followers: 9)
Journal of Signal and Information Processing     Open Access   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 8)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 8)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 8)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 8)
China Communications     Full-text available via subscription   (Followers: 8)
Superconductivity     Full-text available via subscription   (Followers: 8)
IEEE Transactions on Autonomous Mental Development     Hybrid Journal   (Followers: 8)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 8)
International Journal of Antennas and Propagation     Open Access   (Followers: 8)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 8)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 8)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 7)
Power Electronic Devices and Components     Open Access   (Followers: 7)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 7)
Nanotechnology, Science and Applications     Open Access   (Followers: 7)
IEEE Magnetics Letters     Hybrid Journal   (Followers: 7)
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Metrology and Measurement Systems     Open Access   (Followers: 6)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 6)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 6)
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access   (Followers: 6)
International Journal of Electronics     Hybrid Journal   (Followers: 6)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 6)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 6)
Journal of Power Electronics     Hybrid Journal   (Followers: 6)
Annals of Telecommunications     Hybrid Journal   (Followers: 6)
Electronic Markets     Hybrid Journal   (Followers: 6)
Energy Storage Materials     Full-text available via subscription   (Followers: 6)
IEEE Transactions on Services Computing     Hybrid Journal   (Followers: 5)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 5)
Journal of Optoelectronics Engineering     Open Access   (Followers: 5)
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 5)
Journal of Field Robotics     Hybrid Journal   (Followers: 5)
Journal of Electronics (China)     Hybrid Journal   (Followers: 5)
Batteries & Supercaps     Hybrid Journal   (Followers: 5)
IEEE Pulse     Hybrid Journal   (Followers: 5)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal   (Followers: 4)
Networks: an International Journal     Hybrid Journal   (Followers: 4)
EPE Journal : European Power Electronics and Drives     Hybrid Journal   (Followers: 4)
Advanced Materials Technologies     Hybrid Journal   (Followers: 4)
Frontiers in Electronics     Open Access   (Followers: 4)
Wireless and Mobile Technologies     Open Access   (Followers: 4)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
IEEE Transactions on Haptics     Hybrid Journal   (Followers: 4)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 4)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 4)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 4)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Informatik-Spektrum     Hybrid Journal   (Followers: 3)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 3)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 3)
Advancing Microelectronics     Hybrid Journal   (Followers: 3)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 3)
IETE Journal of Education     Open Access   (Followers: 3)
Superconductor Science and Technology     Hybrid Journal   (Followers: 3)
Sensors International     Open Access   (Followers: 3)
e-Prime : Advances in Electrical Engineering, Electronics and Energy     Open Access   (Followers: 3)
EPJ Quantum Technology     Open Access   (Followers: 3)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 3)
Transactions on Electrical and Electronic Materials     Hybrid Journal   (Followers: 2)
ACS Applied Electronic Materials     Open Access   (Followers: 2)
IET Smart Grid     Open Access   (Followers: 2)
Energy Storage     Hybrid Journal   (Followers: 2)
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal   (Followers: 2)
Australian Journal of Electrical and Electronics Engineering     Hybrid Journal   (Followers: 2)
Journal of Information and Telecommunication     Open Access   (Followers: 2)
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 2)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 2)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Journal of Nuclear Cardiology     Hybrid Journal   (Followers: 2)
ECTI Transactions on Electrical Engineering, Electronics, and Communications     Open Access   (Followers: 1)
IET Energy Systems Integration     Open Access   (Followers: 1)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 1)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 1)
IEEE Letters on Electromagnetic Compatibility Practice and Applications     Hybrid Journal   (Followers: 1)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Електротехніка і Електромеханіка     Open Access   (Followers: 1)
Open Electrical & Electronic Engineering Journal     Open Access   (Followers: 1)
IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology     Hybrid Journal   (Followers: 1)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Transactions on Cryptographic Hardware and Embedded Systems     Open Access   (Followers: 1)
International Journal of Hybrid Intelligence     Hybrid Journal   (Followers: 1)
Ural Radio Engineering Journal     Open Access   (Followers: 1)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
Edu Elektrika Journal     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 1)
Automatika : Journal for Control, Measurement, Electronics, Computing and Communications     Open Access  
npj Flexible Electronics     Open Access  
Elektronika ir Elektortechnika     Open Access  
Emitor : Jurnal Teknik Elektro     Open Access  
IEEE Solid-State Circuits Letters     Hybrid Journal  
IEEE Open Journal of Industry Applications     Open Access  
IEEE Open Journal of the Industrial Electronics Society     Open Access  
IEEE Open Journal of Circuits and Systems     Open Access  
Journal of Electronic Science and Technology     Open Access  
Solid State Electronics Letters     Open Access  
Industrial Technology Research Journal Phranakhon Rajabhat University     Open Access  
Journal of Engineered Fibers and Fabrics     Open Access  
Jurnal Teknologi Elektro     Open Access  
IET Nanodielectrics     Open Access  
Elkha : Jurnal Teknik Elektro     Open Access  
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Jurnal Teknik Elektro     Open Access  
IACR Transactions on Symmetric Cryptology     Open Access  
Acta Electronica Malaysia     Open Access  
Bioelectronics in Medicine     Hybrid Journal  
Chinese Journal of Electronics     Open Access  
Problemy Peredachi Informatsii     Full-text available via subscription  
Technical Report Electronics and Computer Engineering     Open Access  
Jurnal Rekayasa Elektrika     Open Access  
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Visión Electrónica : algo más que un estado sólido     Open Access  
Telematique     Open Access  
International Journal of Nanoscience     Hybrid Journal  
International Journal of High Speed Electronics and Systems     Hybrid Journal  
Semiconductors and Semimetals     Full-text available via subscription  

        1 2 | Last   [Sort alphabetically]   [Restore default list]

Similar Journals
Journal Cover
IEEE Transactions on Antennas and Propagation
Journal Prestige (SJR): 1.309
Citation Impact (citeScore): 5
Number of Followers: 81  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0018-926X
Published by IEEE Homepage  [228 journals]
  • IEEE Transactions on Antennas and Propagation

    • Free pre-print version: Loading...

      Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • IEEE Transactions on Antennas and Propagation

    • Free pre-print version: Loading...

      Abstract: Various battery systems are discussed so that the user can make informed decisions on selection, installation design, installation, maintenance, and testing of stationary standby batteries used in uninterruptible power supply (UPS) systems. UPS battery charging and converter components relation to the selection of the battery systems is described. Design requirements of the UPS components are beyond the scope of this document. Battery back-up systems for dc-output rectifiers are also beyond the scope of this document.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Institutional Listings

    • Free pre-print version: Loading...

      Abstract: Presents a listing of institutions relevant for this issue of the publication.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Welcome Message From the New Editor-in-Chief

    • Free pre-print version: Loading...

      Authors: Konstantina S. Nikita;
      Pages: 10006 - 10006
      Abstract: It is with great excitement and honor that I am taking over the role of Editor-in-Chief of the IEEE Transactions on Antennas and Propagation (TAP). I am grateful to the Administrative Committee of the IEEE Antennas and Propagation Society for having entrusted me with the leadership of its flagship journal. Breakthroughs in antennas and propagation and their convergence with cutting-edge technologies are a key enabler for next-generation applications which can advance science, knowledge, and, ultimately, society. TAP provides the ideal forum to accomplish this by facilitating the communication of the most interesting and impactful studies across all sub-fields in antennas and propagation. I am excited for the opportunity to support this mission.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • 3-D Printed 3-D Near-Field Focus-Scanning Lens for Terahertz Applications

    • Free pre-print version: Loading...

      Authors: Geng-Bo Wu;Yuan-Song Zeng;Ka Fai Chan;Shi-Wei Qu;Jeffrey Shaw;Chi Hou Chan;
      Pages: 10007 - 10016
      Abstract: This article introduces a novel near-field focus (NFF) lens antenna with a three-dimensional (3-D) focus-steering capability operating at terahertz (THz) frequencies. The antenna consists of a pair of thin discrete dielectric lenses (DDLs) placed above a stationary feed horn. First, we demonstrate that the DDL doublet’s in- plane synchronous counter-rotation and co- rotation could scan its focus radially and azimuthally, respectively. A multi-focus synthesis method that compensates the required transmission phases at multi-focus points is developed to further improve its NFF-steering performance. The DDL-based antenna can realize 3-D focus-scanning using a combination of rotation and linear translation mechanisms. The 3-D printing is adopted to fabricate the THz antenna to simplify the manufacturing process and reduce the cost. Both numerical and experimental results demonstrate that the 15 mm-diameter antenna prototype can scan its focus in a 3-D cylindrical space with a diameter of 29 mm and a length of 8 mm at 300 GHz. The proposed 3-D focus-scanning antenna with a large field of view (FoV) of 72° will open new avenues for fast 3-D THz imaging applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • 60 GHz Electronically Tunable Leaky-Wave Antenna Based on Annular Surface
           Plasmon Polariton Media for Continuous Azimuth Scanning

    • Free pre-print version: Loading...

      Authors: Anirban Sarkar;Duc Anh Pham;Sungjoon Lim;
      Pages: 10017 - 10031
      Abstract: This article proposes a single-layered electronically tunable annular surface plasmon polariton (SPP)-based leaky-wave antenna at 60 GHz for continuous azimuthal beam scanning. Initially, the groundless annular SPP transmission line is designed having specialized feeding mechanism which is operational at 60 GHz under SPP mode. Periodic radiating semicircular patches are incorporated into the vicinity of the TL that form an additional momentum caused to convert the slow-wave SP mode to radiating leaky-mode and placement of extra metallic ground makes the radiated beam unidirectional. Furthermore, implementation of the varactor diodes with imposed suitable switching conditions make the geometry electronically tunable to achieve a continuous complete azimuth coverage. The theoretical predictions, numerical simulations and the experimental validations of the proposed structure show good agreement. The proposed antenna show an overall scanning range of 275°, peak gain of 19.9 dBi with average sidelobe level of −10 dB and minimum cross polar level of −20 dB. Availing the benefits from the low-profile compactness and improved performance, the proposed groundless LWA appears as a promising candidate for integration in 60-GHz mm-wave applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An On-Body Matched Differentially Fed Magnetoelectric Dipole Antenna for
           Head Imaging Systems

    • Free pre-print version: Loading...

      Authors: Hui Chen;Kwai-Man Luk;
      Pages: 10032 - 10046
      Abstract: An on-body matched differentially fed magnetoelectric (ME) dipole antenna is proposed for the head imaging system to detect intracranial hemorrhage (ICH). The ME dipole with its differential feed achieves a wide impedance bandwidth of 137% from 0.45 to 2.4 GHz. The antenna exhibits unidirectional and symmetrical radiation patterns in the near-field region, leading to a stable main beam toward the 2-D imaging domain inside the human head. The high front-to-back ratio (FBR) above 18 dB is realized in the whole frequency band by this antenna. The values of specific absorption rate (SAR) always remain safe level under 0.82 W/kg in the entire band with an input power of 10 dBm. To validate the detection capability of the proposed antenna, a head imaging system composed of eight antenna elements in a co-polarization state is designed and fabricated. The reconstructed 2-D images of the head interior using a confocal imaging algorithm demonstrate the successful detection and localization of the circular bleeding area as small as 3 mm in radius numerically and 5 mm in radius experimentally, and it has the capability to detect multiple bleeding areas of the human brain, which indicates the head imaging system has the potential to be used in clinical trials.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Sub-Terahertz Wideband Stacked-Patch Antenna on a Flexible Printed
           Circuit for 6G Applications

    • Free pre-print version: Loading...

      Authors: Md Hedayatullah Maktoomi;Zisong Wang;Huan Wang;Soheil Saadat;Payam Heydari;Hamidreza Aghasi;
      Pages: 10047 - 10061
      Abstract: In this article, a wideband aperture-coupled stacked-patch (ACSP) antenna on a flexible material for wireless applications at the WR-08 band is presented. It is shown that conventional designs of ACSP fail to achieve a large bandwidth at this frequency range, and a novel design methodology is proposed. We first propose a broadband impedance matching between the input port and the slot aperture based on two-section wideband distributed network (TWBDN). We also propose a TWBDN matched stacked patch (TMSP) network based on constant VSWR circles to attain broadband matching between the slot aperture and patches in an ACSP. To facilitate the measurements, a novel low-loss transition from a ground-signal-ground (GSG) port to a feedline is proposed. The proposed structure suppresses surface waves induced in the WR-08 band by placing via arrays around the feedline, which largely reduces unwanted resonance modes, thereby leading to uniformly high radiation efficiency across the band. The measured results of the fabricated antenna closely follow the simulations, and a measured peak gain of 7.95 dBi and $S_{11}leq -10$ dB across a wide frequency range from 90 to 128.5 GHz is achieved.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Near-Field Meta-Steering Antenna System With Fully Metallic Metasurfaces

    • Free pre-print version: Loading...

      Authors: Foez Ahmed;Muhammad U. Afzal;Touseef Hayat;Karu P. Esselle;Dushmantha N. Thalakotuna;
      Pages: 10062 - 10075
      Abstract: In the near-field meta-steering method, the near electric-field phase distribution is dynamically altered by rotating a pair of phase-gradient metasurfaces that are typically made out of dielectric lattices or metal patterns printed on bonded dielectric substrates. As a lightweight alternate, a new class of fully metallic metasurfaces (MMs) is proposed in this article. The lack of dielectrics not only substantially reduces the cost and weight but also increases its potential in space and high-power applications. More importantly, the new MMs are designed such that they can be made by cutting narrow slots in fully planar thin metal sheets, retaining structural rigidity while reducing the complexity, cost, and weight. The same MM works for any polarization. Each cell in the new MMs has close to ideal phase shift and transmission magnitude greater than −0.9 dB. A prototype was designed and fabricated to validate this MM-based beam-steering concept in the Ku-band. The maximum measured steering range in zenith is ±42°, with a full 360° steering in the azimuth. The measured 3 dB gain bandwidth is 700–800 MHz (5.6%–6.4%), and the measured gain variation (scan loss) when steering over the whole range is 2.2–4.5 dB. The weight density and thickness of each MM are 0.88 g/cm2 and $0.8lambda _{0}$ , respectively. Including the feed, the total antenna height is $4.9lambda _{0}$ .
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Multi-Element Fully Decoupled Inverted-F Antennas for Mobile Terminals

    • Free pre-print version: Loading...

      Authors: Jiangwei Sui;Cuixia Huang;Yi-Feng Cheng;
      Pages: 10076 - 10085
      Abstract: In this article, a multielement fully decoupled linearly placed inverted-F antenna (IFA) array is proposed for mobile terminals. A hybrid decoupling method is used to mitigate the mixed types of mutual couplings among the multiple IFAs: introducing multiple decoupling capacitors for the couplings of two back-to-back IFA pairs and T-shaped mode transformers for the remaining couplings. The decoupling capacitors not only decouple the back-to-back IFA pairs but also broaden the impedance bandwidth of each IFA. The T-shaped mode transformer transforms the concerned antenna from an IFA mode into a balanced loop mode, preventing the induced current on the victim IFAs of the face-to-face and back-to-face pairs. One four-element example and one eight-element example are designed and measured to justify the proposed decoupling concept. The measured results of the four-element IFAs show that after decoupling, all the six mutual couplings among the four IFAs are reduced by about 10 dB from 3.3 to 3.8 GHz, with average total efficiencies throughout the band improving from 57% to 72% for IFA 1 and from 47% to 55% for IFA 2. An eight-element IFA array is built utilizing the pattern diversity of two proposed four-element IFA blocks, achieving inter-block isolation of better than 20 dB. And a six-element linear IFA array is also designed to prove the generality of the proposed method.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Out-of-Band RCS Reduction of HF/VHF Whip Antenna Using Curved AMC
           Structures

    • Free pre-print version: Loading...

      Authors: Ying Tian;Huotao Gao;Wang Yao;Xiaojun Huang;Fei Peng;Le Yu;
      Pages: 10086 - 10094
      Abstract: The whip antennas used for HF/VHF band communication on the vehicles or ships are generally larger in length and diameter. It would be of great significance if it could be easily hidden from microwave detection radar searches. Aiming at the lower RCS of whip antenna in X-band and maintaining the original impedance and radiation characteristics under high-power input, we propose a whip antenna integrating a novel curved artificial magnetic conductor (AMC) to achieve the RCS reduction in X-band. The backscattering of the cylinder can be dispersed by using the 180° phase difference cancellation principle of different AMC structures, and the mechanism is demonstrated by simulation and experiment. The measurements are in good agreement with the simulations, and the measurement results indicate that in the band of 8–12 GHz, the backward RCS is reduced by an average of 11.2 dBsm in VV polarization and by 10.2 dBsm in HH polarization. Moreover, the proposed whip antenna can be applied to high-power HF/VHF transmitting systems, and the withstand voltage can reach 15 kV (continuous output above 10 kW). This method has important theoretical significance and practical values for the whip antenna in practical engineering applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An Unconventional Shape Memory Alloy Low-Power Ratchet for Reconfiguring
           the Polarization of a Moiré Pattern-Based Antenna

    • Free pre-print version: Loading...

      Authors: Joe Taoum;Elie Shammas;Joseph Costantine;
      Pages: 10095 - 10103
      Abstract: In this article, a novel polarization reconfigurable antenna based on the Moiré effect is proposed. The presented design exploits substantial changes in the overlapped Moiré patterns to minimize the needed actuation for antenna reconfiguration. The novel antenna design is based on stacking two circular FR4 substrates on top of a truncated edge rectangular patch antenna. The top layers of both the substrates are milled into horizontal stripes forming the Moiré patterns. One of these substrates is fixed with respect to the antenna, while the second one rotates with respect to the fixed substrate. Upon rotation, these stripes from the two substrates overlap in pattern, which shapes the antenna. As a result, the antenna design is capable of switching its polarization scheme between vertical, horizontal, and circular with left-hand orientation. In addition, the Moiré patterns can also enhance the directivity and gain of the proposed antenna. The reconfiguration’s mechanical actuation is achieved via a nontraditional ratchet mechanism that uses shape memory alloys (SMAs). This realized actuation system is fast, flexible in its positioning, has low energy expenditure, and minimizes interference with antenna operation. An antenna prototype is fabricated and tested where measured results match the simulated performance.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Millimeter-Wave Dual-Band Dual-Polarized SIW Cavity-Fed Filtenna for 5G
           Applications

    • Free pre-print version: Loading...

      Authors: Rong Lu;Chao Yu;Yuanwei Zhu;Xiaoyue Xia;Wei Hong;
      Pages: 10104 - 10112
      Abstract: This article presents a millimeter-wave (mmWave) dual-band dual-polarized filtenna, which can achieve desirable out-of-band rejection for 5G applications. The dual-band dual-polarized antenna element consists of two fully-shielded quarter-mode substrate integrated waveguide (FSD-QMSIW) cavities and a dual-band stacked ring antenna. Two parts are coupled through the slot on the ground. The cavities are completely enclosed by the metal holes and copper cover to eliminate radiation loss. The loaded slots can tune the frequencies of the first two modes in the FSD-QMSIW cavity for dual-band operation. The inherent transmission null between the dual modes is generated to improve the stopband attenuation. To verify the proposed method, a dual-band dual-polarized filtenna with a three-order filtering function and four radiation nulls is designed and fabricated. The −10 dB impedance bandwidth can effectively cover 5G n258 (24.25–27.5 GHz) and n260 (37–40 GHz) bands in the measurement. The gains of two polarizations drop over 20 dB between the two bands. A four-element filtenna array is constructed to test its beam-scanning ability and further integrated with active beamformer integrated circuits (ICs). The measured results show that the fabricated filtenna array maintains satisfactory out-of-band rejection performance and can be one of the most promising 5G communication candidates.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Compact Wideband Multi-Beam Antenna for VHF/UHF Directional Networking
           Applications

    • Free pre-print version: Loading...

      Authors: Mirhamed Mirmozafari;Ruyu Ma;Fikadu T. Dagefu;Nader Behdad;
      Pages: 10113 - 10122
      Abstract: We propose a wideband multibeam circular array antenna for directional networking applications at VHF/UHF frequencies. We introduce a directional antenna element by combining the radiation patterns of a monopole and a loop element. Combining the figure-eight-shaped and omnidirectional radiation patterns of the loop and the monopole antenna results in a directional antenna element. We demonstrate that a significantly larger bandwidth can be achieved by moderately relaxing the size constraints placed on the antenna element. A circular array consisting of eight of these radiating elements was developed. This array has a low profile, fitting in a 4 $times $ 4 $times $ 1 ft3 volume. The antenna shows a well-matched frequency response with S11 below −10 dB over an octave frequency bandwidth of 225–450 MHz. The good impedance matching of the array is maintained if the array elements are individually excited (e.g., to provide eight beams) or if multiple adjacent elements are excited together to provide fewer, more directional beams. We validated our simulation results by fabricating and experimentally characterizing a 3:1 scaled model of the proposed antenna. The proposed array can achieve gain values of 6–8 dBi within its operational bandwidth if each radiating element is excited individually. This gain increases to 10–12 dBi by exciting three adjacent elements.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Synthesis of Circularly Polarized Cylindrical Microstrip Antennas

    • Free pre-print version: Loading...

      Authors: Diego F. Mona Boada;Daniel C. Nascimento;
      Pages: 10123 - 10131
      Abstract: A set of new formulations derived from the cavity model (CM) that significantly improve the design of cylindrical single probe-fed circularly polarized rectangular microstrip antennas (CPRMAs) are presented in this article. Comprehensive analysis shows that differentiation of the dominant modes effective loss tangents in the far-field expressions gives rise to new closed-form design equations suitable for electrically thin antennas, extending the applicability and improving the CM accuracy for electrically small and large radii cylinders. Furthermore, a function is proposed to estimate the minimal number of significant terms needed in the far-field infinite series to portray the fields radiated by the antenna accurately. The proposed formulations are also used as part of an iterative CM-based algorithm that fully solves the issue of synthesizing a cylindrical CPRMA for a user-defined input impedance. Several antenna examples are compared to full-wave simulations to demonstrate the algorithm’s accuracy. To validate the proposed formulations, a right-hand circularly polarized cylindrical antenna prototype is designed and built to operate at 1.575 GHz over a cylinder with a radius of 25 mm. Comparisons between theoretical and experimental results show excellent agreement.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • High-Contrast Low-Loss Antenna: A Novel Antenna for Efficient Into-Body
           Radiation

    • Free pre-print version: Loading...

      Authors: Allyanna Rice;Asimina Kiourti;
      Pages: 10132 - 10140
      Abstract: We present a biocompatible high-contrast low-loss antenna (HCLA) designed for efficient into-body radiation for applications as diverse as medical telemetry, sensing, and imaging. The HCLA is wearable with a compact size of 2.62 cm3 and operates across the 1–5 GHz bandwidth. The quasi-bowtie antenna is loaded with a high-contrast (i.e., alternating layers of high- and low-permittivity materials) and low-loss dielectric to improve directivity and gain into the biological tissues. Measurement results at 2.4 GHz are in good agreement with simulations and show 5.72 dB improvement in transmission loss over the most efficient into-body radiator reported in the past. At the high end of the frequency bandwidth, the simulation results for two antennas placed across each other with tissue in between show ~12.5 dB improvement in transmission loss. The HCLA is fabricated with stable, low-loss materials that allow for repeatability and consistency in the fabrication process, thus addressing the limitations of the current state-of-the-art. It is also made from biocompatible materials that enable it to be placed directly on the skin for real-world implementation. In this article, we discuss the operation principle and design of the HCLA, its transmission performance, radiation patterns, and specific absorption rate (SAR).
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Analysis, Design, and Measurement of Directed-Beam Toroidal
           Waveguide-Based Leaky-Wave Antennas

    • Free pre-print version: Loading...

      Authors: Shu-Lin Chen;Richard W. Ziolkowski;Bevan Jones;Y. Jay Guo;
      Pages: 10141 - 10155
      Abstract: Leaky-wave antennas (LWAs) have been widely investigated for wireless systems. Most LWAs reported to date are open-path based, i.e., their guided traveling waves follow a non-closed path. A substrate-integrated (SI) toroidal waveguide-based LWA is developed in this article. A coaxial-fed probe structure effectively excites traveling waves that propagate along a closed path in the toroidal waveguide. Inverted L- and planar helical-shaped radiators, whose pickup structures extract power from the waveguide through its top wall, are introduced to radiate, respectively, linearly-polarized (LP) and circularly-polarized (CP) directed beams. The dispersion properties of the closed waveguide’s traveling wave are determined and the associated propagation phase along circular paths with specific radii guides the placement of these radiators to achieve a directive beam at a specified angle. Prototypes of both the LP and CP toroidal LWA (TLWA) systems were fabricated and tested. Good agreement between the simulated and measured results was obtained. The measurements of the compact, low-cost LP and CP prototype systems confirm they radiate beams pointed in their distinctly different, specified directions with realized gains of 13.2 dBi and 13.9 dBic, respectively, at 9.75 GHz.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Novel Surface-Independent Textile Fully Woven UHF RFID Tag

    • Free pre-print version: Loading...

      Authors: Samuel Ver Hoeye;Miguel Fernández;Leticia Alonso;Carlos Vázquez Antuña;Pascal Ghekiere;Javier Ardura Casas;
      Pages: 10156 - 10165
      Abstract: In this work, a UHF broadband surface-independent textile fully woven radio frequency identification (RFID) tag is presented. The antenna is composed of two stacked multilayer fabric pieces in which the shaped conductive and dielectric surfaces are part of the woven structure. In addition, a novel technique for the integration of the RFID chip in the woven structure was developed, providing a maximum integration level and making possible the manufacturing of the tag in a single step using conventional machinery from the textile industry. A tag prototype was experimentally characterized, showing a 12.5 m read range under a $pm 60,, {}times {}pm 60^circ $ angular range, when using a circularly polarized interrogator device with 35.2 dBm effective isotropic radiated power (EIRP).
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Control of Orbital Angular Momentum Regimen by Modulated Metasurface
           Leaky-Wave Antennas

    • Free pre-print version: Loading...

      Authors: Amrollah Amini;Homayoon Oraizi;
      Pages: 10166 - 10176
      Abstract: In this article, we present the design procedure of modulated metasurface leaky-wave antennas (MMLWAs) to generate coaxial superposition of vortex beams with several orbital angular momentum (OAM) states. Based on the flat optics (FO) technique and aperture field estimation (AFE) method, an analytical framework is proposed to facilitate the implementation of MMLWAs generating multiple topological charges in the OAM regimen. Furthermore, using the spectral analysis that has been derived from the proposed model, we have shown that the symmetry of aperture shape can affect the purity of the mode. Also, the perfectly symmetric circular shape is introduced as an ideal choice for high-purity vortex generation. This single aperture antenna with embedded monopole feed can be an appropriate alternative to more complex vortex beam generators such as spiral phase plates and circular antenna arrays. The validity of the proposed analytical method has been studied by designing two structures with petal-like vortex beams.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Anisotropic Complementary Metantenna for Low Sidelobe Radiation and Low
           In-Band Co-Polarized Scattering Using Characteristic Mode Analysis

    • Free pre-print version: Loading...

      Authors: Yan-He Lv;Ren Wang;Bing-Zhong Wang;Zhi Ning Chen;
      Pages: 10177 - 10186
      Abstract: An anisotropic complementary metantenna (ACMA) is proposed for the integration of low sidelobe radiation and low in-band co-polarized (IBCP) scattering with the aid of characteristic mode analysis (CMA). With the guidance of CMA, the proposed ACMA evolving from a conventional metantenna (MTA) not only generates a coding phase distribution for low scattering but also restores broadside radiation modes like a uniform MTA. With the IBCP conditions set to $x$ -polarization and the band around 9 GHz, the ACMA is constructed by mixing two types of double-layer anisotropic complementary metasurface (MTS) unit cells. Two desired characteristic modes of ACMA are simultaneously excited by a substrate integrated waveguide (SIW) cavity through dual bow-tie slots. Both the simulation and experiments demonstrate that the proposed ACMA achieves both the $x$ -polarized broadside radiation with sidelobe level below −18.9 dB and IBCP scattering levels below −17.8 dB over the frequency range from 8.87 to 9.78 GHz.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Low-Profile Uni-Cavity High-Gain FPC Antenna Covering Entire Global 2.4
           GHz and 5 GHz WiFi-Bands Using Uncorrelated Dual-Band PRS and Phase
           Compensation AMC

    • Free pre-print version: Loading...

      Authors: Jiaran Qi;Qiming Wang;Feiyang Deng;Zhi Zeng;Jinghui Qiu;
      Pages: 10187 - 10198
      Abstract: A design methodology of the dual-band Fabry–Perot-cavity (FPC) antenna is proposed, realizing dual-broadband high gain and keeping the simplicity of one low-profile resonant cavity. A ray optics model is applied to obtain the phase resonance condition for dual-band FPC antennas. The proposed antenna employs a tightly stratified partial-reflective-surface (PRS), an artificial-magnetic-conductor (AMC) ground, and a dual-band microstrip feed. The PRS modulates independently the dual-band reflection coefficient to maintain a large amplitude and a positive phase gradient. Meanwhile, an AMC ground is distinctively employed to compensate for the transmission phase difference of the lower band when the cavity height meets half the wavelength of the upper one, enabling eventually a low-profile uni-cavity. Furthermore, a dual-band microstrip feed with two asymmetric slots is customized as the primary radiator. Detailed electromagnetic studies are carried out to illustrate the operating mechanisms of these components. Finally, a proof-of-concept prototype is fabricated covering the entire global 2.4 and 5 GHz WiFi bands. The measurement results agree well with the simulation, and the 3 dB gain bandwidths of 7.2% and 16.2% with peak gains of 13.6 and 15.0 dBi over two wide bands of 2.42–2.60 and 5.1–6 GHz are achieved, respectively, with a single cavity height of 26.8 mm.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Dual-Band Dual-Circularly-Polarized Slot Antenna With Stable In-Band
           Gain and Reduced Frequency Ratio Under Triple Resonance

    • Free pre-print version: Loading...

      Authors: Yanhui Xu;Lei Zhu;Neng-Wu Liu;Mei Li;
      Pages: 10199 - 10206
      Abstract: In this article, a dual-band dual-circularly polarized (CP) narrow slot antenna with stable in-band gain and reduced frequency ratio (FR) is proposed by resonating the $0.5lambda $ -, ${it lambda }$ -, and $2{it lambda }$ -modes. For this purpose, two critical issues are significantly investigated and explored. The first effort is attempted to construct two pairs of orthogonal polarization with opposite rotation, i.e., ( ${it lambda }$ - and $0.5{it lambda }$ -modes) and ( $0.5{it lambda }$ - and $2{it lambda }$ -modes), by properly reshaping the equivalent magnetic currents of the slot radiator. Another attempt is to reallocate these modes in proximity to each other in virtue of stub-loaded technique and ensure them to resonate in the designated sequence of ${it lambda }$ -, $0.5{it {lambda }}$ -, and $2{it lambda }$ -modes instead of the inherent sequence. With these improvements, the dual-CP performance can be successfully realized for our designed antenna. Finally, for experimental verification, a dual-band dual-CP slot antenna in virtue of the proposed design approach is implemented and tested. It proves that the left- and right-hand CP radiation patterns toward the ${z}$ -axis are satisfactorily obtained around 1.88 and 2.39 GHz by simultaneously employing the triple resonance, thus revealing a small FR of 1.27. Moreover, the dual operation bands hold stable in-band gains of about 2.8 and 3.5 dBic. In addition, the CP antenna still maintains the single-layer, single-fed, and single-radiator properties, which evidently confirms the validity and effectiveness of the proposed design.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Circular-Polarization-Selective Metasurface and Its Applications to
           Transmit-Reflect-Array Antenna and Bidirectional Antenna

    • Free pre-print version: Loading...

      Authors: Lin-Xiao Wu;Ke Chen;Tian Jiang;Junming Zhao;Yijun Feng;
      Pages: 10207 - 10217
      Abstract: In this article, a cascaded metasurface (MS) with circular-polarization-selective properties is proposed, which can achieve high reflection for left-handed circular polarization (LCP) and high transmission for right-handed circular polarization (RCP). Such MS, constructed by cascading two kinds of MS sheets, can conduct decoupled geometric phase modulations for the LCP reflection channel and RCP transmission channel by respectively rotating the two elements in the two MS sheets. In order to show its practical applications, first, the proposed MS is applied to design a reconfigurable circularly polarized (CP) transmit-reflect-array antenna (TRA) that can be switched between a high-gain LCP transmitarray antenna and a high-gain LCP reflectarray antenna (RA) dependent on the polarization state of the feed antenna. The simulated results validate its function-switchable and high-gain characteristics. Second, a CP bidirectional antenna is designed utilizing the proposed MS and validated by a fabricated prototype with good agreement between the measured and simulated performances. The results indicate that the joint bandwidth (BW) for both forward and backward aperture efficiencies larger than 20% and axial ratios smaller than 3 dB is about 16% (9.4–11 GHz), across which the antenna realizes bidirectional high-gain and high-purity LCP radiations.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Compact Wide-Beam Circularly Polarized End-Fire Antenna Combining Ground
           Radiation Mode and Vertically Polarized Mode

    • Free pre-print version: Loading...

      Authors: Li Guo;
      Pages: 10218 - 10225
      Abstract: A compact wide-beam endfire antenna with ground radiation mode and vertically polarized mode for circular polarization (CP) is presented in this article. The antenna is constructed based on a configuration of coupled-mode patch antenna (CMPA), which consists of two coupling cavities with a shorting wall, and can generate vertically polarized modes. The CP is realized through a pair of orthogonally polarized modes of horizontal and vertical polarizations. Meanwhile, rendering them acquires an equal amplitude and a 90° phase difference. The horizontally polarized radiation mode is realized through inserting a crossed ground slot. Offset probe feed is used to excite all the radiation modes and introduce an additional phase shift for the CP. A set of offset ground slots (OGSs) are then applied to perturb the electromagnetic coupling of the modes and adjust the phase and magnitude of the radiating electric fields (E-fields). Several effects are synthesized, which results in a wide-beam circularly polarized (CP) endfire radiation. Aiming to improve the radiation performances, a cavity-backed planar reflector was applied in the experiment. Simulated and measured results are detailed and analyzed, which demonstrate that the measured 3 dB axial ratio (AR < 3 dB) bandwidth (ARBW) ranges from 3.385 to 3.428 GHz (1.2%), and the peak gain can be up to 3.4 dBi if the planar reflector is added. The measured half-power beamwidth (HPBW) and 3 dB ARBW can be up to 88°/114° and 53°/112° at 3.4 GHz, respectively. The antenna size (excluding the reflector) is maintained at $0.49lambda _{0}times 0.25lambda _{0}times 0.017lambda _{0}$ , where $lambda _{0}$ is the wavelength in free space, performing a compact-configuration.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Miniature Long-Range Ceramic On-Metal RFID Tag

    • Free pre-print version: Loading...

      Authors: Ildar Yusupov;Dmitry Dobrykh;Dmitry Filonov;Alexey Slobozhanyuk;Pavel Ginzburg;
      Pages: 10226 - 10232
      Abstract: Radio frequency identification (RFID) is a widely used wireless technology for contactless data exchange between a passive information carrier (tag) and an active interrogation device (reader). Being sensitive to a surrounding environment, RFID tags are usually designed per application. Here, we demonstrate an RFID tag with three essential functions available simultaneously, namely, small footprint, long reading range, and capability of on-metal labeling. Our design is based on a compact high-index ceramic resonator and an inductively coupled small metal ring functionalized with an RFID chip. The tag operates at magnetic dipolar resonance, which interacts with the metal object subject to labeling. Specifically, a 16.5 mm $times16.5$ mm $times12$ mm footprint device, placed on a 40 cm $times40$ cm metal sheet, was successfully interrogated from 22 m with no violation of international effective isotropic radiated power (EIRP) standards. Currently, it is the smallest on-metal RFID tag with a reading range of over 20 m. Multifunctional miniature long-range ceramic tags are attractive for use in numerous practical applications, including the Internet of Small Things (IoST) and many others.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • 915 MHz Miniaturized Loop Conformal Antenna for Capsule Endoscope

    • Free pre-print version: Loading...

      Authors: Chunyan Xiao;Sihui Hao;Yueping Zhang;
      Pages: 10233 - 10244
      Abstract: High-performance miniaturized antennas are one of the goals that have been pursued in the design of wireless communication systems for implantable medical devices. In this article, a 915 MHz novel-shape loop antenna conforming to the inner wall of the capsule is developed by comprehensively adopting meander and symmetrical structure patch, folding technique, and vector current reversal technique. Through electromagnetic simulation, testing, and experimentation, the antenna shows good characteristics such as small size, ultra-wideband, circular polarization, strong robustness, and safety. Specific performances include the following: 1) the size of the developed miniaturized loop conformal antenna is only 30.5 mm $times $ 4.6 mm $times $ 0.05 mm and the maximum gain is −21.5 dBi at 915 MHz, which solves the problem of low gain due to the small antenna radiation area; 2) the antenna has a 4.5 GHz ultra-wideband impedance matching bandwidth ( $vert S_{11}vert < -10$ dB) from 0.5 to 5 GHz. Even if the parameters such as the implantation depth and the thickness of the capsule shell change, or there exists a wireless power transfer system, the antenna can still cover the required frequency band with strong robustness; and 3) the specific absorption rate (SAR) of human tissues radiated by the antenna is far lower than the safety limit in IEEE standards and ICNIRP guidelines. The experimental platform using pork to simulate human tissues was built for antenna performance testing and communication testing. The measurement results verified the good resonance performance, radiation characteristics, and omnidirectionality of the developed antenna. The antenna link loss model is also given, which has bee- used in wireless communication and localization.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Infinitesimal Dipole Modeling From Sparse Far-Field Patterns for
           Predicting Electromagnetic Characteristics of Unknown Antennas

    • Free pre-print version: Loading...

      Authors: Jung-Hoon Han;Woosang Lee;Young Dam Kim;
      Pages: 10245 - 10252
      Abstract: The identification of unknown antennas and analysis of electromagnetic wave vulnerability are important for effective attacks and/or protection in high-power electromagnetics (HPEM). Using electromagnetic clues, antenna modeling becomes possible, and its electromagnetic properties can be analyzed by predicting area-wide radiation patterns. To model an antenna, an infinitesimal dipole modeling (IDM) technique, utilizing clues from sparse far-field patterns, was used in the present study. The IDM approach obtained the equivalent infinitesimal dipole (ID) for the antenna configuration current using Green’s function. The sparse far-field pattern was determined for a movement trajectory, using air reconnaissance. Random far-field data acquisition paths were considered cumulatively in the 1–10 range in this case. The approach also used external exposure information about the antenna, such as the operating frequency and size. For simulations and measurements, a ridged-horn antenna operating at 2.4 GHz was used. The overall radiation pattern reconstructed using the IDM approach was correlated at 0.78 when one path was considered in the simulations. As the considered paths were accumulated, the correlation tended to increase, with the correlation for ten paths exceeding 0.98. The estimated radiation pattern characteristics of antennas can be utilized for communication reception characteristics and/or electromagnetic wave vulnerability analysis.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Designing and Implementing Sliding Gain/Pattern Controller Belt for
           Heat-Sink Antennas Operating at C-Band

    • Free pre-print version: Loading...

      Authors: Selcuk Helhel;Zeynep Kocaman;
      Pages: 10253 - 10260
      Abstract: The foremost method to exhaust heat sourced from electronic devices is to use heat sinks. However, in practice, these structures behave as actual antennas and cause interference problems. The selected heat sink like many others is performing like a real antenna whose gain at 4.9 GHz is ~ 7 dBi both in simulation and measurement. In this study, a novel gain (radiation pattern) controlling belt made up of a metamaterial (MTM) structure was designed and dressed to the heat-sink antenna. The effect of the position of the belt on the antenna pattern is investigated. The sliding position of the belt which allows for dynamic gain control varies the antenna gain between 3.38 and 7.36 dBi (~ 7 dB in ${theta }$ angle and ~ 9 dB in ${emptyset }$ angle). Maximum gain enhancement reaches up to 18.43 dB and maximum suppression ratio reaches up to 21.36 dB for the entire angle.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Switched Planar Multicoil Transmitter Antenna Designed With Nonuniform
           H-Field Forming for Small Device Localization

    • Free pre-print version: Loading...

      Authors: Ashwani Sharma;Vivek Kumar Srivastava;
      Pages: 10261 - 10269
      Abstract: To monitor 3-D position and orientation of a small device having planar receiver (Rx) coil, a switched multicoil transmitter (Tx) antenna is proposed by adopting time-divisional approach. The existing multifrequency methods require eight or more input ports to feed the coils with multifrequency signals for localization. In contrast, the proposed Tx antenna is driven by a single frequency source and uses only three input ports for reduced complexity. Moreover, the multiple coils of the proposed antenna are optimally grouped to form nonuniform magnetic-field distribution using three switches (SWs) in such a manner that better localization accuracy is achieved as compared to the multifrequency design. Rigorous analysis and simulations are performed to investigate the performance of the proposed design and localization approach. To validate the claim, experimental study results proved the potential of the proposed antenna employed for tracking a planar Rx in applications like medical robots, navigation of people with limited vision, virtual reality, etc.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Conformal Four-Antenna Module for Capsule Endoscope MIMO Operation

    • Free pre-print version: Loading...

      Authors: Yanyang Wang;Binke Huang;Sen Yan;
      Pages: 10270 - 10285
      Abstract: In this article, a four-antenna module in a capsule endoscopy is proposed for multiple-input multiple-output (MIMO) operation to achieve the purpose of real-time transmission of high-resolution images with high data rates. For compactness, the proposed design adopts conformal architecture and fully utilizes the inner wall space of the capsule body to accommodate four antennas in the very limited space of the capsule endoscope. For the availability of MIMO operation, three different technical approaches are used to decouple or improve the isolation between neighboring antenna elements and between diagonal antenna elements. System considerations (interaction between the electronic components and the antenna in the endoscope) and specific absorption ratio (SAR) evaluation are performed to verify the robustness and human safety of the proposed design, respectively. In addition, link margin analysis and MIMO channel parameter studies are carried out to verify the wireless telemetry performance and MIMO operation performance, respectively. Antenna prototypes were fabricated and implanted in minced pork for ex-vivo measurements (S-parameters, gain, and radiation patterns). The measured overlapping impedance bandwidth of the four antenna elements is 120 MHz, which can fully cover the 915 MHz industrial scientific medical (ISM) band. The measured isolation between the neighboring antenna elements and the diagonal antenna elements is better than 20 and 10 dB, respectively. The measured maximum peak realized gain is −18.1 dBi.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An Impedance Relation and Its Application in Broadband Antenna Design

    • Free pre-print version: Loading...

      Authors: Jun Shu;Yue Ping Zhang;
      Pages: 10286 - 10293
      Abstract: A triangular monopole antenna and a bitriangular slot antenna are designed and measured, respectively, in order to validate a relation between the input impedances of such noncomplementary antennas. The first application of the newly validated impedance relation is demonstrated with the creation of nonself-complementary antennas, which consist of the triangular monopole and the bitriangular slot. As expected, the nonself-complementary antennas indeed exhibit broad impedance bandwidths and stable radiation patterns. Furthermore, the novel nonself-complementary antennas have the advantages of simpler structures and feed than those of the existing nonself-complementary antennas. Hence, they can be easily and inexpensively manufactured.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Planar Switching Integrated Quadrant Coil Antenna to Form Widespread
           Switched Polarized H-Field for Misalignment Resilient WPT System

    • Free pre-print version: Loading...

      Authors: Vivek Kumar Srivastava;Ashwani Sharma;
      Pages: 10294 - 10303
      Abstract: This article presents a planar switching integrated quadrant coil antenna to mitigate lateral and angular misalignment problems in near-field wireless power transfer (WPT) applications. To allow a completely free receiver movement, both the misalignment problems are concurrently addressed by forming widespread distributions of switched polarized H-field in the receiver region. To achieve this, current circulations through the four quadrant coils composing the proposed antenna are judiciously controlled to form three orthogonal H-field components. For lateral misalignment mitigation, the widespread field distributions are obtained by using a field-forming approach for optimizing the antenna parameters. To produce the switched polarized H-field for angular misalignment mitigation, time-switching of the orthogonal H-field components is performed. This switching operation is realized by three double pole double throw (DPDT) switches interconnecting the coils and integrated within the design for a cost-effective planar antenna solution. The fabricated prototype is measured and the experimental results are corroborated with the analysis. The results demonstrate the potential of the proposed antenna to simultaneously mitigate both the misalignment problems for medium-range WPT of small devices, such as medical implants, wireless endoscopy capsules, and wearable devices, which are allowed to freely rotate and displace.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Efficiency Improvement of Smartphone Antennas Using Higher-Order Mode
           Suppression Under Characteristic Mode Analysis

    • Free pre-print version: Loading...

      Authors: Yi Luo;Lei Zhu;Ying Liu;Yunxue Xu;Nengwu Liu;Shuxi Gong;
      Pages: 10304 - 10317
      Abstract: Radiation efficiency is one of the key parameters for smartphone antennas. However, the actual mechanism governing radiation efficiency remains unclear, and a few works have been published. This work is an attempt to extend the theory of characteristic modes (TCMs) to the lossy smartphone antenna for gaining insight into what causes efficiency variation and realizing efficiency improvement. Compared with the classical TCM, the CM analysis (CMA) adopted in this work has the capacity to handle lossy smartphone antenna. By using such an analysis approach, we find, quite interestingly, that suppressing the higher-order modes is an effective optimization strategy to enhance efficiency. Then, an optimized antenna with considerable improvement in efficiency is proposed. Finally, to meet the requirement of practical application, the additional LC circuit and through holes are introduced into this proposed optimized antenna. GSM 900 of 890–960MHz can be covered by this finally proposed antenna, and the measured peak total efficiency is improved from 26% to 43%. Due to the attractive features of small heights (4 mm) and tiny clearances (0.25 mm), the proposed designs are promising for application in a smartphone with a full-view display and thin profile.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Influence of Permeability Dispersion on Radiation of BAW Antenna: Modeling
           of Multiphysics Dynamic Coupling

    • Free pre-print version: Loading...

      Authors: Junru Li;Hongmei Dong;Xinghong Pan;Chunrui Peng;Xiuxiu Gan;Yang Gao;Wanchun Ren;Xuefeng He;
      Pages: 10318 - 10326
      Abstract: Coupling of multiphysics including electrodynamics, elastodynamics, magnetodynamics, and electromagnetic (EM) radiation is involved in the operating process of bulk acoustic wave (BAW) antenna. There is still no good way to design the structure and evaluate the performance of the antenna in theory. Therefore, the multiphysics dynamic coupling model of the antenna is constructed by uniting Newton’s equation for acoustic wave, Maxwell’s equation for EM wave, and Landau–Lifshitz–Gilbert (LLG) equation for spin wave with constitutive relations of multiferroic materials to discuss the dispersion law of permeability and magnetomechanical coupling factor for the magnetostrictive layer. The importance of consistency between ferromagnetic resonance (FMR) frequency and BAW resonant frequency is demonstrated. The analysis shows that both increasing the anisotropic field or the saturation magnetization and decreasing the FMR linewidth are beneficial to improving the internal energy conversion efficiency and the average radiated power for BAW antenna. In addition, a micromagnetic module is introduced into finite element analysis (FEA) software to simulate the precession of unit magnetic moment at different frequencies. Thus, the analytical model is verified from the perspective of power absorption.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Conformal Parallel Plate Waveguide Polarizer Integrated in a Geodesic Lens
           Antenna

    • Free pre-print version: Loading...

      Authors: Freysteinn V. Vidarsson;Oskar Zetterstrom;Astrid Algaba-Brazález;Nelson J. G. Fonseca;Martin Johansson;Lars Manholm;Oscar Quevedo-Teruel;
      Pages: 10327 - 10337
      Abstract: Here, we propose a low-profile polarizing technique integrated in a parallel plate waveguide (PPW) configuration, compatible with fully metallic geodesic lens antennas. The geodesic shape of the antenna is chosen to resemble the operation of a Luneburg lens. The lens is fed with 11 waveguide ports with 10° separation producing 11 switchable beams in an angular range of $pm mathrm{50}^{circ }$ . Two metallic polarizing screens are loaded into the aperture of the antenna to rotate the electric field from a vertical linear polarization, which is the polarization of the transverse electromagnetic (TEM) mode supported in the lens, to a $+ mathrm{45}^{circ }$ linear polarization. Since the polarizing unit cells are integrated into the aperture of the antenna, the final design is compact. In addition, the size of the polarizing unit cells is about $0.55lambda $ at the central frequency of operation making the antenna suitable to produce an array formed of stacked lenses. A prototype of the antenna in the $text{K}_{text {a}}$ -band was manufactured and tested, verifying the performance obtained in simulations.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Low-Profile and Wideband Unidirectional Antenna With Ferrite Loading for
           UHF Applications

    • Free pre-print version: Loading...

      Authors: Ping Yin;Zongliang Zheng;
      Pages: 10338 - 10346
      Abstract: A low-profile and wideband unidirectional antenna with ferrite loading is presented for ultrahigh-frequency (UHF) applications. This design comprises a slotted bowtie antenna with parasitic elements placed 50 mm over a ground plane. A small amount of ferrite loaded on the center of the ground plane plays a crucial role in improving the performance of the low-profile antenna. The ferrite used here is a new type of magnetodielectric material with relatively high permeability and permittivity, as well as low magnetic and dielectric loss. The loaded ferrite introduces an additional phase change of the electromagnetic field reflected by the ground to improve the impedance matching, bandwidth, efficiency, and gain of the low-profile antenna. The evolution process and mechanism of the proposed antenna are elaborated. For validation, an optimized antenna prototype was fabricated and measured. The measured results are consistent well with their simulations, which shows the realized gain of 7.2–9 dBi over $vert text{S}_{11}vert le -10$ dB impedance bandwidth of 38% (480–705 MHz). The overall profile of this antenna is only $0.08lambda _{0}$ , where $lambda _{0}$ is the free-space wavelength at the lowest frequency of operation.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Dynamics Analysis of a VLF Linear Antenna in an Anisotropic Magnetoplasma

    • Free pre-print version: Loading...

      Authors: Hui Ran Zeng;Tong He;Kai Li;
      Pages: 10347 - 10354
      Abstract: The motion of a very-low-frequency (VLF: 3–30 kHz) orbiting antenna across the Earth’s magnetic field will generate the Lorentz force, which not only compromises the efficiency of the antenna, but also causes it to fall out of orbit over a long time. This article investigates the Lorentz force and dissipated power of a VLF space-borne linear antenna in an anisotropic magnetoplasma as well as the deorbiting time of the system. By considering the inhomogeneity of the current and the effect of ordinary and extraordinary waves, we systematically quantified and analyzed the Lorentz force on the antenna in an anisotropic scenario. The dissipated power and system deorbiting time are then determined by integrating antenna theory and electrodynamics. The results show that the Lorentz force and the power will increase with the antenna length and radius, whereas the deorbiting time will decrease accordingly. It is also found that as the geomagnetic inclination angle increases, the Lorentz force and the power will slightly decrease. The proposed method can estimate the Lorentz force, power, and deorbiting time for arbitrary antennas, low Earth orbital conditions, and VLF ionospheric parameters. This work may also help eliminate the adverse effect and evaluate the deorbiting performance of the VLF space-borne system from an analytical perspective.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Cylindrical Antenna With a Conductively Loaded Slot for Broadband
           Imaging Radar Applications

    • Free pre-print version: Loading...

      Authors: Woong Kang;Seunggyu Yang;Kangwook Kim;Changryol Kim;Seong-Jun Cho;
      Pages: 10355 - 10364
      Abstract: A cylindrical antenna with a conductively loaded slot (CACLS) is designed for broadband imaging radar applications. Through design considerations, such as conductive loading, cylinder termination, and the insertion of an electromagnetic (EM) wave absorber into the cylinder, the proposed CACLS is shown to be able to radiate temporally short and nondispersive pulses. Based on the final design of the antenna, parametric studies pertaining to the time-domain radiation performances depending on the dimension of the cylinder are performed. The CACLS with the determined design parameters is then fabricated and its performances verified through antenna measurements and a radar experiment. In addition to its excellent pulse radiation and reception performance, the realized antenna has a compact and physically robust structure, which makes it potentially suitable for many broadband imaging radar applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Dual-Band Series-Fed Arrays Using Coupled Line Sections With Improved
           Performance

    • Free pre-print version: Loading...

      Authors: Yun-Peng Lyu;Lei Zhu;Chong-Hu Cheng;
      Pages: 10365 - 10377
      Abstract: A new design of dual-band series-fed array (SFA) using coupled line sections with one series-fed network (SFN) and one port is proposed in this article. Compared with the conventional array, the proposed design provides one more degree of freedom in antenna array synthesis. It can realize equal beam angles at two operational frequencies and reduce element spacing to eliminate the grating lobe by virtue of nonlinear phase properties. The parameters have been extensively studied and considered in the analytical analysis. An assessment method of achievable beam angles for dual-band SFAs is proposed and conducted in the entire upper hemisphere. Compared with the conventional array, the proposed dual-band SFA can expand the achievable radiation range with regard to $theta _{mathrm {d1}}$ and $theta _{mathrm {d2}}$ . Its limitations are also analyzed and discussed. Furthermore, in order to realize specified sidelobe level (SLL) at two operational frequencies, the closed-form design formulas are deduced for the proposed dual-band SFA with arbitrary N elements and amplitude distributions. To verify the proposed design concept and synthesis method, a prototype of proposed six-element dual-band SFA with specified $theta _{mathrm {d1}},,= 90^{circ }$ , $theta _{mathrm {d2}},,= 110^{circ }$ , and SLL = −20 dB centered at $f_{1},,=2.1$ GHz and $f_{2},,=3.5$ GHz is designed, fabricated, and tested. The simulated and measured results match well with the theoretical predictions.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Synthesizing Wideband Frequency-Invariant Shaped Patterns by Linear Phase
           Response-Based Iterative Spatiotemporal Fourier Transform

    • Free pre-print version: Loading...

      Authors: Liyang Chen;Yanhui Liu;Yi Ren;Chunhui Zhu;Shiwen Yang;Y. Jay Guo;
      Pages: 10378 - 10390
      Abstract: A new approach for synthesizing wideband frequency-invariant (FI)-shaped patterns is presented. This method is a significant extension of the original iterative spatiotemporal Fourier transform (STFT) method that only deals with wideband FI pencil-beam patterns. Based on the original method, the wideband pattern can be regarded as a spatiotemporal spectral distribution, and the relationship between the spatiotemporal spectral distribution and finite-impulse-response (FIR) filter coefficients can be built as an STFT, which can be efficiently calculated by using 2-D fast Fourier transform (2-D-FFT). To achieve desired FI-shaped pattern performance, the spatiotemporal spectral distribution is iteratively adjusted by two new techniques called wideband pattern shaping and linear phase response (LPR)-based modification. Different from the constant phase response (CPR) processing in the original iterative STFT method, the LPR-based modification uses more relaxed phase requirements, thus releasing much more degrees of freedom. Numerical results show that the proposed method is effective even for very complicated pattern requirements, and it is very efficient in terms of both computation and storage. Besides, the proposed method can take into account the effects of frequency-variant antenna element patterns and mutual coupling in the periodic array structure.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Millimeter-Wave ±45° Dual Linearly Polarized End-Fire Phased Array
           Antenna for 5G/B5G Mobile Terminals

    • Free pre-print version: Loading...

      Authors: Xiaoyue Xia;Fan Wu;Chao Yu;Zhi Hao Jiang;Rong Lu;Yu Yao;Wei Hong;
      Pages: 10391 - 10404
      Abstract: In this article, a millimeter-wave (mmWave) endfire phased array antenna with ±45° linear polarizations is proposed for fifth generation (5G)/B5G mobile communications. The proposed antenna achieves ±45° polarizations by utilizing a modified substrate integrated waveguide (SIW) slot polarizer. The polarizer generates dual orthogonal modes with equal amplitudes and a 0°/180° phase difference, thereby yielding $+ 45^{circ }/- 45^{circ }$ -polarization radiated waves in the far field. In a practical metal-framed mobile phone environment, the ±45 polarizations are verified to provide more balanced radiation patterns and, consequently, a higher polarization-multiple input multiple output (MIMO) efficiency. A prototype of the proposed 1 $times $ 4 array is fabricated and measured, achieving a −10 dB impedance bandwidth of 23.4–30.0 GHz (covers 5G band of n257/n258), with an isolation better than 15.6 dB and a realized gain above 8.9 dBi in the operating bandwidth. A peak gain of 11.4 dBi and a 3 dB scanning range of 87° can be observed at 27.0 GHz. Furthermore, the prototype is characterized on a metal-framed mobile phone platform, experimentally demonstrating its superiority to conventional vertical/horizontal polarized (V-/H-pol) arrays. The validated advantages of the balanced radiation patterns and robust impedance matching make the proposed ±45°-polarization endfire antenna array a promising candidate for mobile terminals in the era of 5G/B5G.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Isophoric Inflating Deflating Exploration Algorithm (I-IDEA) for
           Equal-Amplitude Aperiodic Arrays

    • Free pre-print version: Loading...

      Authors: Daniele Pinchera;Marco Donald Migliore;Gaetano Panariello;
      Pages: 10405 - 10416
      Abstract: We present a deterministic iterative method for synthesizing equal-amplitude aperiodic array radiating patterns with arbitrary upper bounds and are capable of scanning in a wide angular range without violating the sidelobe level constraint. The approach employs the principle of “inflating” and “deflating” the sources to reduce the excitation dynamic of a starting layout iteratively. The proposed approach is flexible since it can start from a regular grid array with variable excitation amplitudes or from a nonuniform aperiodic layout generated with any other synthesis algorithm. Several numerical simulations comparing the proposed approach to some of the algorithms available in the open literature demonstrate the excellent performance of the approach.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Wideband Conformal Transmitarrays for E-Band Multi-Beam Applications

    • Free pre-print version: Loading...

      Authors: Li-Zhao Song;Pei-Yuan Qin;He Zhu;Jia Du;
      Pages: 10417 - 10425
      Abstract: Wideband conformal transmitarrays at E-band are developed for multibeam applications in this article. A triple-layer element with double split rings is presented for wideband transmissions, achieving a 360° continuous phase variation range at 74 GHz with less than 2.3 dB transmission loss. A comprehensive design methodology of multibeam conformal transmitarrays is demonstrated for various platforms with different curvatures. To validate the theoretical analysis, conformal transmitarrays with two different curvatures are designed, fabricated, and measured. Multiple radiation beams are realized between ± 30° and ± 45° for the two prototypes, respectively. Good agreement is obtained between simulation and measurement. The 3 dB gain bandwidths are 30% from 66.5 to 90 GHz, and 27.8% from 68 to 90 GHz for the two designs, respectively, covering the entire E-band.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Shared-Aperture Dual-Polarized Ku-Band and Single-Polarized Ka-Band Phased
           Array Antenna With Scanning Coverage Enhancement

    • Free pre-print version: Loading...

      Authors: Ai Hu Song;Yu Jian Cheng;
      Pages: 10426 - 10435
      Abstract: A dual-polarized Ku-band and single-polarized Ka-band shared-aperture phased array antenna is proposed in this article. The endfire dipole antenna is designed as the radiating element of both bands. To eliminate the shading effect of the horizontal-polarized Ku-band antenna caused by the common ground, the director is loaded on the Ka-band antenna to increase the height of the equivalent phase center of the Ka-band antenna. The high-order mode of the horizontal-polarized Ku-band antenna is excited when the Ka-band antenna scans to a wide angle in H-plane within the frequency range of 33–34 GHz. An etched square ring is loaded on the Ku-band radiating arm to induce the reverse current to prevent such a high-order mode. The scanning blind spots occur at 33 and 35.8 GHz when the Ka-band antenna scans to 50° in E-plane owing to the mutual coupling between the Ka-band antenna and the vertical-polarized Ku-band antenna. A metallic strip is loaded on the vertical-polarized Ku-band antenna to eliminate the blind spot at 33 GHz. The feeding position of the vertical-polarized Ku-band antenna is elevated to eliminate the blind spot at 35.8 GHz. The periodic cell and finite array are simulated to verify the design proposed in this article. The results demonstrate that the design is effective and the beam-scanning coverage reaches $pm mathrm{50}^{circ }$ at both bands. The active voltage standing wave ratio (VSWR) is not greater than 3.5 at 15–17 and 33–36 GHz in the whole beam-scanning coverage. A prototype of the 4 $times $ 4 Ku-band and 8 $times $ 8 Ka-band shared-aperture array is fabricated and measured. The measured results agree well with the simulated ones.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Dual-Circularly Polarized Array Antenna Based on Gap Waveguide Utilizing
           Double-Grooved Circular Waveguide Polarizer

    • Free pre-print version: Loading...

      Authors: Qiannan Ren;Ashraf Uz Zaman;Jian Yang;
      Pages: 10436 - 10444
      Abstract: This article presents a dual-circularly polarized array antenna based on gap waveguide technology operating at E-band. Double-grooved circular waveguide polarizers that utilize two annulus grooves placed at 45° and 135° offset from both excitation ports are used in this work. The operating principles of the polarizer are analyzed. Multilayer design using gap waveguide is implemented on the basis of the polarizer. The antenna consists of six layers, including three layers for the feeding networks, one layer for the polarizer, one layer of back cavity, and another layer of radiating grid. A 2 $times $ 2 unit cell is proposed first and employed to realize an 8 $times $ 8 planar array. Corporate feeding networks that use compact E-plane T-junctions and H-plane T-junctions are proposed. The antenna has been fabricated and verified by measurements. The measured results of S-parameters agree well with the simulation and show that reflection coefficients are better than −10 dB for both circular polarizations (CPs) from 76 to 81 GHz. The measured isolation between the input ports is larger than 25 dB in the operating band. The far-field measurements show that the antenna has realized gain larger than 24 dBi and axial ratios less than 1.5 dB from 76 to 81 GHz at boresight direction.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Scan-Angle-Independent FEM Analysis of Infinite Arrays Based on Spherical
           Harmonic Lattice Sums and the Generalized Scattering Matrix of an Isolated
           Antenna

    • Free pre-print version: Loading...

      Authors: Jesús Rubio;Miguel Á. González de Aza;Juan Córcoles;Rafael Gómez Alcalá;
      Pages: 10445 - 10453
      Abstract: Infinite periodic arrays of antennas that can be individually described by means of spherical modes are analyzed starting from the generalized scattering matrix (GSM) of an isolated element. After computing the GSM of an isolated element with the finite-element method (FEM), a fast postprocessing can be carried out to calculate the response of the element in an infinite array environment by using addition theorems for spherical modes. For this purpose, an efficient computation of lattice sums of spherical harmonics is used. The main advantage of this method is that the antenna is analyzed only once whatever the array lattice or scan angle. In addition, fast frequency analysis can be performed since the starting point is the computation of the isolated antenna with the FEM, which is suitable for fast frequency sweep. The active reflection coefficient and the embedded radiation pattern of the infinite periodic array are calculated for several examples to show the capabilities of the proposed method.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Chaotic-Enabled Phase Modulation in Time-Modulated Arrays for Secure
           Transmission

    • Free pre-print version: Loading...

      Authors: Haotian Li;Yikai Chen;Shiwen Yang;
      Pages: 10454 - 10464
      Abstract: The “time” factor in time-modulated arrays (TMAs) offers a new degree of freedom for securing wireless communication. However, the widely used periodic time modulation introduces limited randomness for eavesdropping receivers, and thus gives weak security. To meet this challenge, this work proposes a TMA with chaotic-enabled phase modulation (CPM) for secure transmission. The proposed CPM technique offers the chaos features of high randomness, unpredictability, and initial condition sensitive characteristic, to increase the information uncertainty for eavesdropping receivers. An optimization-based time sequence design approach is introduced to design optimal CPM time sequences for secure transmission in a given direction. Thus, a variety of security strategies including beam scanning, directional modulation (DM), and chaotic encryption are simultaneously enabled by the optimized CPM time sequence. Moreover, the CPM is a radio frequency (RF)-domain security technique without requiring any baseband modulation modules, which exhibits a simplified hardware architecture. Numerical analysis and experimental results are presented to illustrate the effectiveness of the proposed CPM technique. The results indicate that the security is improved by lowering the bit error rate (BER) between the legitimate receiver and the transmitter, and reducing the mutual information between eavesdropping receivers and the transmitter.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Metasurface-Assisted Broadband Circularly Polarized Folded Reflectarray
           Antenna

    • Free pre-print version: Loading...

      Authors: Xianjiang Zhong;He-Xiu Xu;Lei Chen;Jianqiang Hou;Hao Wang;Wentao Li;Yan Shi;Xiaowei Shi;
      Pages: 10465 - 10474
      Abstract: In this article, a novel design of broadband circularly polarized (CP) folded reflectarray (FRA) antenna is proposed. The CP FRA consists of two kinds of metasurfaces (MSs) and a linearly polarized (LP) open waveguide antenna as the feeding source. The bottom MS functions as the main reflector, which is capable of realizing cross-polarization conversion and beam focusing simultaneously. The upper MS is utilized as a subreflector, which could reflect LP wave coming from the feeding source and transmit its orthogonal counterpart into CP wave. For demonstration, the MS-assisted CP FRA antenna is fabricated and measured. Numerical results are consistent with experimental ones, illustrating a peak gain of 24.1 dBi and a peak aperture efficiency of 51% at 9.9 GHz. The 3 dB gain bandwidth and 3 dB axial ratio (AR) bandwidth are achieved as 27.5% (8.8–11.6 GHz) and 43.9% (8–12.5 GHz), respectively. The proposed CP FRA provides a new avenue to realize broadband high-efficiency CP antenna, which may find great potentials in modern wireless communication systems.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Wideband L/X-Band Shared-Aperture Phased Array Antenna for SAR
           Applications

    • Free pre-print version: Loading...

      Authors: Wen-Liang Zhou;Shi-Wei Qu;Mingyao Xia;Shiwen Yang;
      Pages: 10475 - 10484
      Abstract: In this article, a wideband shared-aperture phased array antenna is proposed for synthetic aperture radar (SAR) applications. A metal cavity-backed slot antenna and a slot antenna are used as the L- and X-band antenna elements, respectively. Notably, the X-band antenna elements are mounted on top of the L-band ones, and their interactions are successfully isolated by loading a layer of frequency selective surface (FSS). The FSS layer reflects the electromagnetic waves in X-band and allows transmission of the L-band electromagnetic waves, making the shared-aperture antenna work properly in L- and X-bands. Furthermore, a circular patch is designed to improve the bandwidth of the X-band antenna. Simulations indicate that the proposed antenna has impedance bandwidths of 46% in X-band (7.5–12 GHz) and 21% in L-band (1.7–2.1 GHz). Moreover, the X-band antenna can scan up to ±60° in the E-plane and ±30° in the H-plane with voltage standing wave ratio (VSWR) below 3. To verify the design method, a shared-aperture antenna prototype, which consists of $6times6$ X-band elements and one L-band element, has been fabricated and measured. Finally, the measured results agree well with the simulated ones.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Interferometric Phase Transmitarray for Spatial Power Combining to Enhance
           EIRP of Millimeter-Wave Transmitters

    • Free pre-print version: Loading...

      Authors: Xiaoxuan Guo;Yu Luo;Zhi Ning Chen;Ningning Yan;Wenxing An;Kaixue Ma;
      Pages: 10485 - 10493
      Abstract: An interferometric phase transmitarray is proposed for spatial power combining to enhance the equivalent isotropically radiated power (EIRP) of the millimeter-wave (mmW) transmitters. The study shows that the multiple beams emitting from the ideal point sources located at different positions are combined into one beam to radiate in the boresight direction of the transmitarray, namely, achieving spatial power combining. As an example, the prototyped transmitarray fed by two patch antennas operating over the bandwidth of 23–27 GHz shows that with the spatial power combining, the proposed antenna achieves the combined gain realized by two feeds of 19.6 dBi at boresight 2.5 dB higher than the realized gain of the single feed, so that the EIRP of the two-feed transmitarray is enhanced by 5.5 dB because of 2.5 dB from the gain enhancement of two-feed transmitarray and 3 dB by the two-way power combining.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • 3-D Printed Dielectric Dome Array Antenna With ±80° Beam
           Steering Coverage

    • Free pre-print version: Loading...

      Authors: Lin Xiao;Shi-Wei Qu;Shiwen Yang;
      Pages: 10494 - 10503
      Abstract: An efficient design of a 3-D printed dielectric dome array (DDA) antenna featuring ultrawide-angle beam scanning is presented in this article. Instead of using optimization tools, the inner and outer contours of the dielectric dome lens (DDL) are determined by the derived phase distribution $phi (theta)$ over a dome surface $r(theta)$ . The scan gain of the DDA can be manipulated by properly choosing the defined scan amplification factor $K(theta)$ of the DDL. After determining the contours of the DDL, two finite-by-infinite 1-D DDA models are constructed to predict the E- and H-plane scanning performances, respectively, wherein both the full-wave performances of feed array and the effect of multiple reflections at the air–dielectric interfaces are considered. Since the phase distribution over the planar array is nonlinear due to the presence of the DDL, the array excitation phases are optimized by the particle swarm optimization (PSO) method with the optimization goal of the maximum gain at each scan angle. As a proof of concept, a 3-D printed DDL fed by an $8 times 8$ E-shaped patch array at 20 GHz is manufactured and tested. When combined with the DDL, a ±60° scan range of the planar array can be extended to ±80° with relatively flat scan gain. The experimental results are in acceptable agreement with simulations, verifying the feasibility of the DDL design.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Experimental Demonstration of High Optically Transparent Reflectarrays
           Using Fine Metal Line Structure

    • Free pre-print version: Loading...

      Authors: Biao Chen;Bian Wu;Hao-Ran Zu;Jian-Qiang Hou;Tao Su;
      Pages: 10504 - 10511
      Abstract: In this article, we present a novel design method to achieve optically transparent reflectarrays (RAs) with fine metal line (FML) structure. With this design method, an RA element with a peak return loss of 2.8 dB and a phase variation of 360° is achieved during 12.5–14.5 GHz. Compared with the reported transparent RAs, we first realize wide phase variation, high transparency and low return loss simultaneously. The proposed element is composed of FML pattern, quartz glass substrate, and indium tin oxide (ITO) ground. The FML pattern consists of a metal cross and a folded square ring with a linewidth of 50 $mu $ m made by a photolithographic process. For verification, three $20 times 20$ -element RAs with pencil beam and orbital angular momentum (OAM) beam have been arranged, simulated, fabricated, and measured. The measured results agree well with the simulations. The measured optical transmittance of all prototypes is greater than 82% at any position. The proposed FML structure greatly improves the transmittance and has potential for the applications in transparent communication devices.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Circularly Polarized Elliptical Cavity-Backed Patch Antenna Array for
           Millimeter-Wave Applications

    • Free pre-print version: Loading...

      Authors: Guang-Hua Sun;Hang Wong;
      Pages: 10512 - 10519
      Abstract: This work introduces cost-effective solution for a millimeter-wave (mmW) antenna array development. We suggest an elliptical cavity-backed patch antenna array to achieve a wideband and high-gain circularly polarized (CP) at mmW frequencies. The whole array only uses two PCBs and a metallic fixture to build. We introduce a new configurable subarray with $2times $ 1 radiating elements that are formed by two partially overlapped elliptical cavities to generate the radiation together with the driven patches of the subarray. The subarray can produce a wide impedance bandwidth of 37%, a wide 3 dB axial ratio (AR) bandwidth of 29.6%, and a maximum gain of 11.6 dBic. Based on the result from the subarray, we design a 32-element antenna array by a $4 times $ 4 antenna array configuration. The power distribution is realized by a 1-to-16 full-corporate feed network. The measured results show that the proposed CP array obtains an impedance bandwidth of 31.5% and a 3 dB AR bandwidth of 24%. In addition, the gain of the array is from 19.1 to 21 dBic within the 3 dB AR bandwidth. With wide impedance and AR bandwidths, the proposed antenna array can find potential applications in long-range mmW communications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Novel Coupling Cancellation Method by Loading Planar Path for Wideband
           High-Isolation Wide-Scanning Millimeter-Wave Phased Array

    • Free pre-print version: Loading...

      Authors: Lizheng Gu;Wanchen Yang;Shaowei Liao;Quan Xue;Wenquan Che;
      Pages: 10520 - 10530
      Abstract: A novel coupling-cancellation method by loading planar path is proposed and applied in the millimeter-wave phased array for wide-angle scanning. By employing the improved decoupling stubs with weak radiation first, an extra introduced wideband equal-magnitude and anti-phase path is generated to cancel the inherent coupling path. The principle of the proposed method is investigated by the equivalent circuits and the full-wave simulation. Based on this method, a high-isolation 1-D phased array using low-temperature-cofired ceramic (LTCC) process is designed and fabricated. The planar paths are placed symmetrically between the subarrays and its radiation polarization is coincident with the antenna elements, resulting in high isolation and enhanced boresight radiation null-fill of subarrays. The measured isolation is below 20 dB within the relative bandwidth of 16.7% and the maximum scanning angle is ±60°. Moreover, the proposed method can be expectedly extended to large-scale arrays.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Two-Dimensional Image Theory-Based Surface-Mounted Linear Array With
           Azimuth Wide-Angle Scanning Performance

    • Free pre-print version: Loading...

      Authors: Ren Wang;Xin Liu;Yi-Feng Cheng;Mu-Sheng Liang;Bing-Zhong Wang;
      Pages: 10531 - 10542
      Abstract: This article focused on broadening the azimuth plane scanning range of surface-mounted linear arrays. First, 14 kinds of basic radiation models were theoretically analyzed, and the basic model with a 180° covered main lobe was pointed out. Afterward, a wide-beam surface-mounted antenna was designed using an in-phase-reflection electromagnetic bandgap structure based on the selected element model. Finally, an azimuth plane wide-angle scanning linear array with wide-beam surface-mounted elements was arranged, decoupled, and evaluated. This array can scan its beam in the range of 90° ± 85° in the azimuth plane with a 3 dB gain fluctuation, which verified the effectiveness of the proposed theoretical model.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Synthesizing Shaped-Beam Cylindrical Conformal Array Considering Mutual
           Coupling Using Refined Rotation/Phase Optimization

    • Free pre-print version: Loading...

      Authors: Ming Li;Yanhui Liu;Shu-Lin Chen;Jun Hu;Y. Jay Guo;
      Pages: 10543 - 10553
      Abstract: A novel method of synthesizing shaped-beam cylindrical conformal array by rotating the antenna elements and optimizing their excitation phases is presented. Rotation of antennas on curved surface is mathematically described by rotating its vectorial active element pattern (VAEP) in its local coordinate system (LCS). Then the scalar patterns and polarization unit vectors of all the rotated VAEPs are properly transformed and then interpolated at a unified angle sampling grid in a common coordinate system, where they are summed to obtain an approximated array expression. With this expression, element rotations and phases can be optimized using the constriction factor particle swarm optimization (CF-PSO) to synthesize desired shaped-beam pattern with controlled sidelobe level (SLL) and cross-polarization level (XPL). However, since rotations on curved surface introduce considerable variations to the element curvature and mutual coupling (MC), the synthesized array pattern would have considerable errors. A refined strategy is adopted then to improve the synthesis accuracy. The proposed method uses uniform amplitude weighting, thus saving many unequal power dividers. Three typical shaped pattern synthesis examples are provided to show the effectiveness of the proposed method. A cylindrical array prototype with 24 rotated U-slot loaded patch antennas is fabricated and measured for practical validation.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Description of Microwave Circuits via the Reduced-Basis Method Giving
           Physical Insight

    • Free pre-print version: Loading...

      Authors: Valentín de la Rubia;
      Pages: 10554 - 10568
      Abstract: A description of electromagnetics by means of the reduced-basis method (RBM), which gives physical insight, is detailed. Contrary to what has been previously done to get further insights from the electromagnetic behavior, a reliable reduced-order model completely describing a microwave circuit in a frequency band of interest is carried out. Following a theoretical analysis starting from time-harmonic Maxwell’s equations, we identify the dominant contributions to electromagnetics in a band of analysis. Making use of the reliable reduced-order model, we present the electromagnetic information in that reduced-order model in a more insightful manner, using a specific dynamical system representation of electromagnetics. As a result, a full-wave coupling matrix completely describing electromagnetics in the band of analysis is identified, where no narrowband approximation is considered, such as it is the case in classical coupling matrix circuit theory. No approximation is taken into account other than carrying out the analysis in a given frequency band, which can be arbitrarily large. The proposed approach provides a way to understand electromagnetics, where a full-wave coupling matrix allows the description of electromagnetics in a band of interest as a simple physically insightful circuit, and not the other way around. Finally, several real-life microwave circuits, such as a dual-mode filter and diplexer, will illustrate the capabilities and efficiency of the proposed approach.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Quasi-Static Homogenization of Glide-Symmetric Holey Parallel-Plate
           Waveguides With Ultra-Wideband Validity

    • Free pre-print version: Loading...

      Authors: Boris Fischer;Guido Valerio;
      Pages: 10569 - 10582
      Abstract: Glide-symmetric (G-S) waveguides made of metallic metasurfaces are a wideband, low-loss, low-cost, and conformable alternative to dielectric materials for the design of antenna lenses at millimeter waves. However, computing the effective refractive index of glide-symmetric waveguides with existing full-wave analysis techniques results in cumbersome parametric studies for each new design. This article presents a new analytic homogenization technique for glide-symmetric holey parallel-plate waveguides (PPWs). The dispersion equation of these structures, found by way of mode-matching, is simplified at low frequency using the properties of the modes resonating within the holes, independently of the hole shape. This simplified equation yields a closed-form expression of the effective refractive index, relying on the eigenmodes of the hole cross section. This formula avoids solving a 3-D full-wave problem and is fully analytic in the case of canonical hole shapes. Although derived in the quasi-static regime, it characterizes propagation over an ultrawide band, due to the low dispersive properties of glide symmetric structures. It is a function of the angle of propagation within the waveguide and can thus be used to study anisotropic properties. Its efficiency is demonstrated with the example of glide-symmetric PPWs with rectangular and circular holes.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Surface Susceptibilities as Characteristic Models of Reflective
           Metasurfaces

    • Free pre-print version: Loading...

      Authors: Ville Tiukuvaara;Tom J. Smy;Karim Achouri;Shulabh Gupta;
      Pages: 10583 - 10591
      Abstract: While metasurfaces (MSs) are constructed from deeply subwavelength unit cells, they are generally electrically large and full-wave simulations of the complete structure are computationally expensive. Thus, to reduce this high computational cost, nonuniform MSs can be modeled as zero-thickness boundaries, with sheets of electric and magnetic polarizations related to the fields by surface susceptibilities and the generalized sheet transition conditions (GSTCs). While these two-sided boundary conditions (BCs) have been extensively studied for single sheets of resonant particles, it has not been shown if they can correctly model structures where the two sides are electrically isolated, such as a fully reflective surface. In particular, we consider in this work whether the fields scattered from a fully reflective MS can be correctly predicted for arbitrary field illuminations, with the source placed on either side of the surface. In the process, we also show the mapping of a perfect electric conductor (PEC) sheet with a dielectric cover layer to bianisoptropic susceptibilities. Finally, we demonstrate the use of the susceptibilities as compact models for use in various simulation techniques, with an illustrative example of a parabolic reflector, for which the scattered fields are correctly computed using an integral-equation (IE)-based solver.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Design of Single-Layer Dense Metasurfaces on Irregular Grids Using
           Discrete Dipole Approximation

    • Free pre-print version: Loading...

      Authors: Do-Hoon Kwon;
      Pages: 10592 - 10603
      Abstract: A design technique for single-layer metasurfaces of planar and conformal profiles utilizing nonperiodic, irregular grids for meta-atom placement is presented. Meta-atoms are placed at the node positions in planar and conformal surface grids created by an unstructured mesher. They are represented by point dipoles using the discrete dipole approximation (DDA), and mutual coupling effects from neighboring resonators are accurately evaluated. Each meta-atom is individualized for representing a desired average current density over the corresponding cell area. Examples of fully reflecting metasurfaces using DDA-based individualized meta-atoms exhibit closer-to-ideal performance than identical meta-atoms on the same grid.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Prephase-Based Equivalent Amplitude Tailoring for Low Sidelobe Levels of
           1-Bit Phase-Only Control Metasurface Under Plane Wave Incidence

    • Free pre-print version: Loading...

      Authors: Jiexi Yin;Qi Wu;Haiming Wang;Zhi Ning Chen;
      Pages: 10604 - 10613
      Abstract: A prephase synthesis method is proposed for sidelobe level (SLL) suppression of a 1 bit phase-only control metasurface under plane wave incidence. The array factor of the metasurface with $N times N$ unit cells shows that controlling the number of prephases with varying values over the reflective surface can equivalently control the amplitude. Different from optimizing the prephase distribution, selection of the 0 and $pi /2$ prephases in specific $N$ regions is used to suppress the SLLs. Therefore, the number of parameters in the optimization can be dramatically reduced from $N^{2}$ to ${N}$ . The prephase distribution is then designed based on the optimized number of prephases and a symmetric matrix for SLL suppression in the entire space. The SLLs are further suppressed by optimizing some of the unit cell states based on similar equivalent amplitude tailoring. Simulations and measurements of a set of 1 bit reflective metasurfaces with 20 $times $ 20 unit cells verify that the phase-only control metasurface realizes SLL suppression to −13 dB for multiple beam directions from $- 30^circ $ to 30 ° with a 10° step under normal plane wave incidence.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Low Profile Reflective Polarization Conversion Metasurface With High
           Frequency Selectivity

    • Free pre-print version: Loading...

      Authors: Yu-Tong Zhao;Jun-Jie Zhang;Bian Wu;
      Pages: 10614 - 10622
      Abstract: In this article, a multilayer reflective polarization conversion metasurface with both high-frequency selectivity and low profile is proposed. The frequency selective polarization conversion metasurface (FSPCM) is composed of four metal layers separated by three substrates. The cross-shaped patch on the top layer is connected to the folded microstrip line on the bottom layer with two via holes through the circle slots inside two ground layers, which converts the linearly polarized electromagnetic incident wave into cross-polarized wave after reflection. The second-order response can extend to the third-order response by introducing a coupled half-wavelength microstrip resonator on the bottom metal layer, which achieves high-frequency selectivity with a transmission zero and high polarization conversion rate (PCR) without increasing the thickness. The equivalent circuit analysis, structure simulation, and experimental demonstration are conducted in detail; the frequency selectivity of the fabricated FSPCM at the lower and upper band edge is 94 and 192 dB/GHz, respectively; PCR is more than 97% from 4.85 to 5.12 GHz, and the thickness is only $0.028lambda _{0}$ , where $lambda _{0}$ is the free space wavelength at the center operating frequency. Our findings pave a new way for enhancing the anti-interference capability and electromagnetic compatibility in applications of communication system, microwave imaging, and stealth technology.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Wideband Amplifying Reconfigurable Intelligent Surface

    • Free pre-print version: Loading...

      Authors: Lijie Wu;Kai Lou;Junchen Ke;Jingcheng Liang;Zhangjie Luo;Jun Yan Dai;Qiang Cheng;Tie Jun Cui;
      Pages: 10623 - 10631
      Abstract: We present a C-band amplifying reconfigurable intelligent surface (ARIS) integrated with power amplifier (PA) to enhance the reflected electromagnetic (EM) signals. An aperture-coupled patch element with two orthogonal hourglass-shaped slots is elaborately constructed to ensure a broad operation bandwidth. A power combining and dividing network is also introduced to combine the 2 $times2$ elements into a subarray to reduce the number of PAs and the system cost. The simulation results indicate that the achieved gain of ARIS is 7.7–12.2 dB from 5.0 to 6.0 GHz. A prototype of the proposed ARIS is designed, fabricated, and experimentally verified. The measured results agree well with the simulation. The proposed ARIS is promising for applications in future wireless communication systems for signal enhancement and coverage extension.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Experimental Verification of Backscattering Protection in PTD-Symmetric
           Bifilar Edge Waveguides

    • Free pre-print version: Loading...

      Authors: Iram Nadeem;Valentina Verri;Enrica Martini;Fabio Morgia;Alberto Toccafondi;Maurizio Mattivi;Stefano Maci;
      Pages: 10632 - 10640
      Abstract: This article presents the design and experimental characterization of microwave structures based on parity time-reversal duality symmetric bifilar edge waveguides (PTD-BEWs) realized through a parallel plate waveguide (PPW) loaded by a metasurface. The analyzed structures include transmission lines with bends and multiple line arrangements. Due to their unique symmetry properties, these structures are robust against backscattering, thus resembling the behavior of topological WGs, despite the fact they are reciprocal. This makes it possible to guide the electromagnetic (EM) waves along the edge with low insertion losses and unique matching properties. Measurements, performed in the frequency range between 24 and 32 GHz, have confirmed the feasibility of the theoretical concept.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Unidirectional Curved Surface Plasmon Polariton in a Radially Magnetized
           System

    • Free pre-print version: Loading...

      Authors: Samaneh Pakniyat;Alexander M. Holmes;George W. Hanson;
      Pages: 10641 - 10649
      Abstract: Dynamic manipulation of the surface plasmon polariton (SPP) and wave steering is important in plasmonic applications. In this work, we excite a curved SPP in topological continua by applying a radial magnetic bias. We believe that it is a new technique to create a unidirectional SPP traveling along a curved trajectory. We also derive a Green’s function (GF) model for radially biased plasma, applicable to curved SPPs. We compare the properties of unidirectional curved SPPs with the usual case when an axial bias is applied.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Feasible Extraction Method for Electromagnetic Properties of Multilayer
           Metamaterials With Short-Circuit Termination

    • Free pre-print version: Loading...

      Authors: Ugur Cem Hasar;Gokhan Ozturk;Yunus Kaya;Musa Bute;Muharrem Karaaslan;Joaquim J. Barroso;Omar M. Ramahi;Mehmet Ertugrul;
      Pages: 10650 - 10659
      Abstract: An extraction technique is proposed for electromagnetic characterization of metal-backed multilayer metamaterial (MM) structures demonstrating reflection-asymmetric property. It uses recursive scattering parameters for direct and reversed configurations of a multilayer structure. The algorithm was validated by comparing the extracted electromagnetic properties of multilayer structures composed of different MM unit cells with those determined by one-layer-only S-parameter methods. Two-layer and three-layer multilayer structures composed of MM slabs with C-shaped and $Omega $ -shaped rings and an FR4 material were fabricated and measured for experimental validation. A sensitivity analysis was also conducted to quantitatively evaluate the performance of our method against a small air gap between the multilayer structures and the short-circuit termination and between adjacent MM slabs within these structures. Strong agreement was observed between the resulted obtained using our method and measurements.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Metasurface-Loaded Off-Center Monopoles With Wideband Radiation
           Performance Using Characteristic Mode Analysis

    • Free pre-print version: Loading...

      Authors: Huiwen Sheng;Zhi Ning Chen;
      Pages: 10660 - 10668
      Abstract: A metasurface (MTS)-based reactive impedance surface (RIS) is proposed to load an eccentrically placed monopole above a ground plane for controllable wideband omnidirectional radiation. With the off-center placement, the radiation pattern of the monopole is not omnidirectional anymore, with ripples in the H-plane measured by un-roundness. The RIS is introduced above and in parallel with the finite ground plane and the monopole is placed in the center of the RIS. Characteristic mode analysis (CMA) is used to analyze the RIS-loaded monopole and to reveal the mechanism. It is found that two desired modes determine the bandwidth of the omnidirectional radiation together. The resonant frequency of the RIS mode can be easily tuned by changing the sheet impedance of the RIS. A metal-dielectric-metal constructed MTS is proposed to realize the RIS. The grid impedance of the MTS can be tuned easily by changing the size of the patch in the unit cell. For a single monopole placed off-center above a rectangular ground plane (150 mm $times300$ mm), the impedance bandwidth is increased from 19.6% to 32.4% with $vert text{S}_{11}vert < -10$ dB at $f_{0} =2.5$ GHz. And the maximum un-roundness is reduced by 66.7% from 4.8 to 1.6 dB over the frequency band of 2.2–2.8 GHz. For a two-monopole antenna system with the same ground plane mentioned above, the loading MTS increases the impedance bandwidth of the monopole from 19.2% to 32.4% with $vert text{S}_{11}vert < -10$ dB at $f_{0} =2.5$ GHz. When only one monopole is loaded with MTS in the system, the maximum un-roundness is reduced by 65.5% from 5.5 to 1.9 dB in the frequency band of 2.2–2.8 GHz. When both monopoles are loaded with MTS in the system, the maximum un-roundness is reduced by 40% from 5.5 to 3.3 dB in the frequency band of 2.2–2.8 GHz. The antenna prototypes are fabricated and measured.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • High-Selectivity FA-FA-Based Frequency Selective Surfaces Using
           Magnetoelectronic Dipole Antennas

    • Free pre-print version: Loading...

      Authors: Huawei Lin;Yin Li;Sai-Wai Wong;Kam Weng Tam;Baiyang Liu;Lei Zhu;
      Pages: 10669 - 10677
      Abstract: A new method for frequency selective surface (FSS) with high selectivity, namely, filtenna–filtenna (FA-FA)-based technique, is proposed, which consists of two filtering antennas and impedance matching network. Based on the reciprocity theorem, the radiation null of filtenna can provide a stopband of the proposed FSS. In this work, it is validated by using a periodic array of back-to-back magnetoelectronic (ME)-dipole antennas with split-ring resonators (SRRs), and a slotted GND plane is used to connect the two ME-dipole antennas for impedance matching. Bandpass response of the proposed FSS is realized by the intrinsic high-pass characteristic of ME-dipole antennas and the bandstop characteristic of SRRs. Four transmission zeros (TZs) and three transmission poles (TPs) are generated, exhibiting a high-order filtering response. TZs and TPs are analyzed by equivalent circuit model and current distributions. The 3 dB fractional bandwidth ( ${mathrm {FBW}}_{mathrm {3,dB}}$ ) of 38.5% in the passband and the 20 dB fractional bandwidths $({mathrm {FBW}}_{mathrm {20,dB}})$ of 8.7% in the lower rejection band and 13.8% in upper rejection band are obtained in this design. Finally, a prototype is fabricated and measured to further validate the proposed FA-FA-based technique. Simulated and measured results show that the proposed FA-FA-based FSS is with the distinct advantages, including wide passband, low profile, tunable TZs, and dual-polarized application, which verifies the proposed method of FSSs.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Dual-Band Spin-Decoupled Metasurface for Generating Multiple Coaxial OAM
           Beams

    • Free pre-print version: Loading...

      Authors: Peng Xu;Haixia Liu;Ruijie Li;Kunyi Zhang;Long Li;
      Pages: 10678 - 10690
      Abstract: In this article, we propose a shared-aperture metasurface (MS) combining spin-decoupled strategy to generate four coaxially circularly polarized (CP) beams carrying orbital angular momentum (OAM) at Ku-band and Ka-band. First, the frequency selective surface (FSS) is adopted to suppress the mutual coupling between the Ku-band and the Ka-band. Next, at each band, the spin-decoupled meta-atom is designed to realize the independent control for dual circular polarizations. Subsequently, the designed MS illuminated by CP feed source would generate left-hand CP (LHCP) beam with OAM mode +1 and right-hand CP (RHCP) beam with OAM mode −1 at Ku-band; meanwhile, the LHCP beam with OAM mode +2 and the RHCP beam with OAM mode −2 are generated at Ka-band. Finally, the MS is designed, manufactured, and measured. Both simulated and measured near-field and far-field performance verify that the proposed MS can generate four independent CP OAM beams along the same spatial axis at dual bands. On the other hand, the experimental results and the corresponding theoretical analysis verify that the proposed MS illuminated by a linear-polarized (LP) feed source could also generate eight correlative LP OAM beams at dual bands.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Surface Waves on Non-conducting Structured Interfaces

    • Free pre-print version: Loading...

      Authors: Mathieu Poulin;Maksim Skorobogatiy;
      Pages: 10691 - 10705
      Abstract: Surface waves are demonstrated theoretically to propagate along periodically corrugated surfaces made of non-conductive lossless materials with positive permittivity. An analytic derivation of the surface wave dispersion relation is presented in the case of the deeply subwavelength period of a corrugated structure using impedance boundary conditions (IBCs) at the interfaces. Thus obtained dispersion relation is verified numerically and limitations as well as the physicality of IBCs when modeling surface waves are discussed. Finally, suitable materials, potential experimental realization, and sensing applications of surface waves in the terahertz spectral range are discussed.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Dual-Layer Full-Phase Frequency-Selective Surface for Continuous 2-D
           Beam Scanning

    • Free pre-print version: Loading...

      Authors: Zhuo-Yue Wen;Yong-Ling Ban;Yong Yang;Qiang Sun;Zaiping Nie Nie;
      Pages: 10706 - 10717
      Abstract: Based on the generalized frequency selective surface (FSS) theory, we prove that the dual-layer dual-polarization transmission FSS can achieve 360° phase coverage at a limited loss. As a verification, a dual-layer dual-polarization full-phase unit cell with vias is proposed, which can achieve a phase range of more than 360° under 2 dB transmission loss. In addition, we innovatively apply the proposed dual-layer full-phase FSS to the design of a continuous 2-D beam scanning antenna based on the Risley prism (RP). This scheme effectively reduces the number of dielectric substrate layers required by the phase shifting surface (PSS), reduces the rotating scanning inertia, and effectively improves the aperture efficiency. The measured results show that the maximum scanning range of the 2-D beam scanning antenna can reach ±46° in the elevation plane and 360° in the azimuth plane. When operating at the center operating frequency of 21 GHz, the maximum gain of the antenna is 35.75 dBi with an aperture efficiency of 44.1%.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Generating High-Purity Directive Circularly Polarized Beams From Conformal
           Anisotropic Holographic Metasurfaces

    • Free pre-print version: Loading...

      Authors: Jian Wang;Rui Yang;
      Pages: 10718 - 10723
      Abstract: Using anisotropic holographic metasurfaces to transform the creeping waves into circularly polarized (CP) beams has initiated the quest for tangible applications in different disciplines. However, the present designs are only limited to the planar impedance surfaces with rare studies concerning the linear-to-circular polarization converting holographic metasurface over the conformal platforms. In this article, we demonstrate the perfect transformation of linearly polarized (LP) surface waves into CP waves through cylindrical anisotropic holographic metasurfaces consisting of gradient H-shaped slits etched on the periodic circular patches. Especially, the linear-to-circular polarization conversion rate can always maintain a very high level for the beam synthesis no matter how the curvature of the metasurface changes, and such high-purity CP beams also demonstrate very good quality of steerable characteristics over conformal surfaces. Our approach, using anisotropic holographic metasurfaces to transform the creeping waves into high-purity CP beams, should pave the way for more advanced functional meta-device designs over the nonplanar impedance surfaces.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Physics-Based Greedy Algorithm for Reliable Fast Frequency Sweep in
           Electromagnetics via the Reduced-Basis Method

    • Free pre-print version: Loading...

      Authors: Valentín de la Rubia;
      Pages: 10724 - 10735
      Abstract: A reliable fast frequency sweep model order reduction (MOR) process is detailed. A reduced-basis approximation is taken into account to accurately and efficiently describe the electromagnetic field in a frequency band of analysis. The reduced-basis space is made up of snapshots of the electric field adaptively chosen on a physics-based greedy algorithm. Following a theoretical analysis starting from time-harmonic Maxwell’s equations, in- band eigenresonances are shown to significantly contribute to the electric field in the band of analysis. An impedance matrix transfer function description of the microwave circuit is used and a pole-residue expansion of this matrix-valued impedance transfer function is detailed. A fundamental physical property is identified, from which a straightforward a posteriori error estimator arises, namely, matrix residues in the pole-residue expansion of the impedance transfer function must be rank-1. This cheap computation is well-suited for fast greedy algorithm strategies in adaptive construction of the reduced-basis approximation. Contrary to what has been previously done, a straightforward physics-based greedy algorithm that does not need to scan the whole frequency band of interest to enrich the reduced-basis approximation is proposed. Finally, actual microwave applications illustrate the capabilities and efficiency of the new physics-based a posteriori error estimator in the proposed methodology.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Parallel Boundary Element Method for the Electromagnetic Analysis of
           Large Structures With Lossy Conductors

    • Free pre-print version: Loading...

      Authors: Damian Marek;Shashwat Sharma;Piero Triverio;
      Pages: 10736 - 10750
      Abstract: In this article, we propose an efficient parallelization strategy for the boundary element method (BEM) solvers that perform the electromagnetic analysis of structures with lossy conductors. The proposed solver is accelerated with the adaptive integral method, can model both homogeneous and multilayered background media, and supports excitation via lumped ports or an incident field. Unlike existing parallel BEM solvers, we use a formulation that rigorously models the skin effect, which results in two coupled computational workloads. The external-problem workload models electromagnetic coupling between conductive objects, while the internal-problem workload describes field distributions within them. We propose a parallelization strategy that distributes these two workloads evenly over thousands of processing cores. The external-problem workload is balanced in the same manner as existing parallel solvers that employ approximate models for conductive objects. However, we assert that the internal-problem workload should be balanced by algorithms from the scheduling theory. The parallel scalability of the proposed solver is tested on three different structures found in both integrated circuits and metasurfaces. The proposed parallelization strategy runs efficiently on distributed-memory computers with thousands of CPU cores and outperforms competing strategies derived from existing methods.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An Improved GMRES Method for Solving Electromagnetic Scattering Problems
           by MoM

    • Free pre-print version: Loading...

      Authors: Xinyuan Cao;Mingsheng Chen;Qi Qi;Xiangxiang Liu;Daoping Wang;
      Pages: 10751 - 10757
      Abstract: Method of moments (MoM) is a classical numerical method for analyzing electromagnetic (EM) scattering from various objects. Generalized minimal residual (GMRES) is a kind of widely used solver for linear systems of equations generated by MoM, whose calculation complexity mainly includes two parts, matrix-vector multiplications and the orthogonalization procedure. In order to accelerate the solution of matrix equations arising in MoM, an efficient strategy for constructing nonorthonormal Krylov bases is proposed in this article, which can be introduced into standard GMRES and its variants (e.g., GMRES( $m$ ) and quasi-GMRES) and can be easily combined with the fast approaches for MOM (e.g., FMM and ACA). The principle of the method is described in detail, and the effectiveness is verified by numerical results.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Efficient Full-Wave Modeling of Microwave Components With Interval-Valued
           Electromagnetic Parameters by Polynomial Chaos Expansion-Based DGTD Method
           

    • Free pre-print version: Loading...

      Authors: Yiting Yang;Wen Ming Yu;Huaguang Bao;Dazhi Ding;Tie Jun Cui;
      Pages: 10758 - 10768
      Abstract: An efficient polynomial chaos expansion (PCE)-based discontinuous Galerkin time-domain (DGTD) method is proposed to analyze microwave components with interval-valued electromagnetic (EM) parameters. The proposed method retains the flexibility of the conventional DGTD method in the element-level domain decomposition and parallel computing. Numerical examples with the interval-valued electron density of plasma and permittivity of a dielectric block are presented to demonstrate the accuracy and capability of the proposed method. The scattering from a dielectric sphere with an interval-valued permittivity is evaluated to verify the applicability of the proposed method in unbounded scattering analysis. Numerical results illustrate that the proposed PCE-based DGTD method has great superiority in computational accuracy and efficiency over the Gaussian process (GP) technique and the Monte Carlo (MC) method in both deterministic and stochastic analyses with the interval-valued parameters, and it requires only a single simulation to obtain all results in the high-dimensional interval domains.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • On the Effect of Grid Orthogonalization in Stability and Accuracy of an
           FDTD Subgridding Method

    • Free pre-print version: Loading...

      Authors: Antonio M. Valverde;Miguel Ruiz Cabello;Clemente Cobos Sánchez;Amelia Rubio Bretones;Salvador G. Garcia;
      Pages: 10769 - 10776
      Abstract: We present a general-purpose subgridding (SG) inspired on a simplified orthogonalized integral (OI)-based method, leading to a simple and efficient algorithm with strong stability. It is based on a 2:1 transition ratio between coarse and finer zones and a natural local time-stepping (LTS) strategy to connect the domains. We provide a closed form for the stability condition and prove it heuristically, to show that roughly a 65% time-step reduction is enough to achieve stability. Results for coupling through lossy thin shells, compared with classical subcell impedance boundary methods, confirm the high accuracy of this method.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Computationally Efficient Surrogate-Assisted Design of Pyramidal-Shaped
           3-D Reflectarray Antennas

    • Free pre-print version: Loading...

      Authors: Peyman Mahouti;Mehmet A. Belen;Nurullah Çalık;Slawomir Koziel;
      Pages: 10777 - 10786
      Abstract: Reflectarrays (RAs) have been attracting considerable interest in recent years due to their appealing features, in particular, the possibility of realizing pencil-beam radiation patterns, as in the phased arrays, but without the necessity of incorporating the feeding networks. These characteristics make them attractive solutions, among others, for satellite communications or mobile radar antennas. Notwithstanding, available microstrip implementations are inherently narrow-band and heavily affected by conductor and surface wave losses. RAs based on grounded dielectric layers offer improved performance and flexibility in terms of shaping the phase reflection response. In either case, a large number of variables (induced by the need for independent adjustment of individual unit cell geometries) and the necessity of handling several requirements make the design process of reflectarrays a challenging endeavor. In particular, RA optimization is extremely expensive when conducted at the level of electromagnetic (EM) simulation models, otherwise necessary to ensure reliability. A practical solution is a surrogate-assisted design with the metamodels constructed for the RA unit elements. Unfortunately, conventional modeling methods require large numbers of training data samples to render accurate surrogates, which turns detrimental to the optimization process efficiency. This work proposes an alternative approach with the unit element representations constructed using deep learning with automated adjustment of the model architecture. As a result, design-ready surrogates can be constructed using only a few hundred samples, and the total RA optimization cost is reduced to only a handful of equivalent EM analyses of the entire array. Our approach is validated using an RA incorporating 3-D pyramidal-shaped elements and favorably compared to benchmark techniques. Experimental verification of the obtained design is discussed as well.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Efficient and Robust Shadowing Determination for Mesh-Based Physical
           Optics Analysis

    • Free pre-print version: Loading...

      Authors: Dao P. Xiang;Matthys M. Botha;
      Pages: 10787 - 10799
      Abstract: Visibility status determination for every mesh element/edge with respect to an illuminating source is routinely required in mesh-based physical optics (PO) methods, where the scatterer is represented by subwavelength sized elements. This article presents an optimally efficient shadowing determination algorithm for both plane wave and point source (Hertzian dipole) illumination of large-scale triangle meshes. It is based on a recursive multilevel field-of-view (image space) subdivision buffer approach, whereby a point’s status is determined by only checking against a small subset of elements. It is error-free and formulated to maintain efficiency for inhomogeneous meshes and grazing incidence, which result in concentration of projected elements in small areas of the buffer plane. A key step is to separate the grazing and nongrazing parts of the mesh. Very challenging test cases affirm the algorithm’s expected optimal and robust linear computational cost scaling of $mathcal {O}(N)$ , where $N$ denotes the number of mesh elements. For fixed $N$ , almost constant runtimes under extreme illumination and mesh variations, further demonstrate robustness.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Rigorous Modal Characterization of First- and Second-Order Symmetric
           Waveguides Using Specular Periodic Boundary Conditions in 2D-FEM

    • Free pre-print version: Loading...

      Authors: Gines Garcia-Contreras;Juan Córcoles;Jorge A. Ruiz-Cruz;
      Pages: 10800 - 10810
      Abstract: Symmetries are widely exploited in the electromagnetic characterization of millimeter-wave devices and antennas, as they usually bring an improvement in resource usage and accuracy in full-wave simulations. Given the rising relevance of higher order symmetric devices, a challenge of integrating many different symmetries into compact formulations appears, with the objective of finding synergies and combining the strengths each one separately brings. In this work, we present a 2-D finite element method (FEM) formulation that fulfills this task for arbitrary waveguide cross sections presenting at the same time specular first-order and rotational second-order symmetries. It is based on newly introduced specular periodic boundary conditions (SPBCs), which effectively exploit the best case simulation domain for this problem. Furthermore, they avoid the need of using a mesh matching or projection procedure for periodic boundaries, while also bringing an improvement to mode classification.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Ka-Band Satellite Propagation Experiment at the Guiana Space Centre

    • Free pre-print version: Loading...

      Authors: Charles-Antoine L’Hour;Jean-Pascal Monvoisin;Xavier Boulanger;Laurent Castanet;
      Pages: 10811 - 10819
      Abstract: From January 2017 to December 2021, Office National d’Etudes et de Recherches Aérospatiales (ONERA) and Centre National d’Etudes Spatiales (CNES) operated a beacon receiver able to record the 20.1995 GHz beacon signal of the Amazonas-3 satellite at the Guiana Space Centre in Kourou, French Guiana. A rain gauge was also deployed on site to collect rainfall rate measurements concurrently to beacon data. All years of the experiment, except 2019, had excellent data availability, hence giving four full years of data (2017, 2018, 2020, and 2021). First, the climatic characteristics of French Guiana are shown. Second, the propagation experiment and the data processing methodology are described. Third, the results of the statistical analysis are highlighted and commented. Comparisons are performed with the prediction methods of Recommendation ITU-R P.837-7 (rainfall rate), Recommendation ITU-R P.618-13 (rain attenuation), Recommendation ITU-R P.678-3 (variability of propagation phenomena), and Recommendation ITU-R P.1623-1 (fade dynamics).
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • On the Deficiency of the First-Order Ott–Clemmow Saddle Point Method as
           Applied to the Sommerfeld Half-Space Problem

    • Free pre-print version: Loading...

      Authors: Krzysztof A. Michalski;Juan R. Mosig;
      Pages: 10820 - 10827
      Abstract: The accuracy of the first-order multiplicative (Ott–Clemmow) and additive (van der Waerden) modified saddle point integration methods for the Sommerfeld problem of a vertical Hertzian dipole over a lossy half-space is investigated using two theoretically equivalent formulations with either a positive or a negative image term extracted. It is demonstrated that whereas the additive method leads to the same asymptotic field representation irrespective of the sign of the image, the multiplicative variant yields distinct results in these two cases, both of which differ from the unique result of the additive method. It is further found that the positive-image Ott–Clemmow method yields the well-known Norton formula, but the negative-image variant is inaccurate and predicts a zero field in the on-surface transmitter–receiver configuration. It is also demonstrated that the first-order multiplicative method yields an incomplete representation of the first order in the inverse distance.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Generalized Recursive Vogler Algorithm for Multiple Bridged Knife-Edge
           Diffraction

    • Free pre-print version: Loading...

      Authors: Viet-Dung Nguyen;Ali Mansour;Arnaud Coatanhay;Thierry Marsault;
      Pages: 10828 - 10842
      Abstract: In this article, we consider the problem of estimating diffraction attenuation from the approximation of terrain using a multiple bridged knife-edge model. This model can be considered as a generalization of the well-known multiple knife-edge (MKE) one where spaces between knife-edges are bridged by reflecting surfaces. A series-based-standard solution is presented in the literature but suffers from its very high computational complexity. We, thus, propose to generalize the recursive Vogler algorithm developed for the MKE model to tackle this problem. To reduce complexity, the proposed algorithm exploits the recursive form to avoid repeated calculations of the existing solution. Moreover, we provide a complexity analysis of both the standard algorithm and the proposed algorithm based on the number of computed integrals. Both theoretical and numerical results show that our proposed algorithm is faster than the original one while having identical accuracy, hence proving the effectiveness of our solution.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Rigorous EM Scattering Solution From a Slit in an IBC Plate With Different
           Surface Impedances Placed Between Two Different Chiral Media

    • Free pre-print version: Loading...

      Authors: Hossein Davoudabadifarahani;Behbod Ghalamkari;
      Pages: 10843 - 10850
      Abstract: A Kobayashi potential (KP) method is an accurate and fast technique for analyzing electromagnetic (EM) scattering. In this article, the EM scattering from a slit in an impedance boundary condition (IBC) plate with different surface impedances on its both sides placed on interface of two different chiral media is analyzed by the KP method for both right circularly polarized (RCP) and left circularly polarized (LCP) excitations. A chirality parameter is a more degree of freedom—than dielectrics—presented by a chiral medium to affect the EM scattering. Initially, Fresnel coefficients are calculated as closed-form formulas; then, the slit’s contribution is expressed in terms of unknown weighting functions. Next, the method automatically and analytically satisfies boundary and radiation conditions applying Weber–Schafheitlin (WS) integrals, which leads to infinite summations. The infinite summations are effectively truncated with high accuracy. Finally, the weighting functions and, subsequently, the EM scattering are calculated. A finite-element method (FEM) and a convergence analysis are carried out to validate the formulations. The effects of different parameters of the problem on the EM scattering are also analyzed. It is shown that the maximum scattered fields are occurred at non-specular angles. Also, this solution can be a facilitator to analyze the inverse scattering of the problem to determine the properties of the structure.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A New Correction to the Rytov Approximation for Strongly Scattering Lossy
           Media

    • Free pre-print version: Loading...

      Authors: Amartansh Dubey;Xudong Chen;Ross Murch;
      Pages: 10851 - 10864
      Abstract: We propose a correction to the conventional Rytov approximation (RA) and investigate its performance for predicting wave scattering under strong scattering conditions. An important motivation for the correction and investigation is to help in the development of better models for inverse scattering. The correction is based on incorporating the high-frequency theory of inhomogeneous wave propagation for lossy media into RA formulation. We denote the technique as the extended RA for lossy media (xRA-LM). xRA-LM significantly improves upon the existing noniterative linear scattering approximations such as RA and Born approximation (BA) by providing a validity range for the permittivity of objects of up to 50 times greater than RA. We demonstrate the technique by providing results for predicting wave scattering from piecewise homogeneous scatterers in a 2-D region. Numerical investigation of the performance of xRA-LM for solving direct problems show that xRA-LM can accurately predict wave scattering by electrically large, low-loss scatterers with high complex relative permittivity ( $epsilon _{r}> 50+5j$ ). To the best of our knowledge, this is the first noniterative, linear approximate wave scattering model which has a large validity range in terms of both permittivity and electrical size.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • The Diurnal Variation of the Evaporation Duct Height and Its Relationship
           With Environmental Variables in the South China Sea

    • Free pre-print version: Loading...

      Authors: Lang Huang;Xiaofeng Zhao;Yudi Liu;Pinglv Yang;Jiaqi Ding;Zeming Zhou;
      Pages: 10865 - 10875
      Abstract: Based on data from the European Centre for Medium-Range Weather Forecasts (ECMWF) ECWMF ERA5 Reanalysis (ERA-5) and the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) datasets, the diurnal variation of the evaporation duct height (EDH) in the South China Sea (SCS) and its relationship with environmental variables using the Naval Postgraduate School (NPS) model are analyzed, discussed, and presented. The findings are given as follows. First, the EDH diurnal variations are primarily influenced by the sea-land thermal contrast, with the major influencing variables being the relative humidity (RH) and the near-surface wind speed (WS), followed by the air-sea temperature difference (ASTD). Secondly, the areas where the EDH and the RH are highly correlated are mostly in northern SCS, and the two variables are negatively correlated. Besides, in southeastern SCS, the EDH has a greater and positive correlation with the WS. Seasonal changes can be found in areas where the EDH is highly correlated with the ASTD, primarily to the northwest of Luzon Island in winter and the east coast of Vietnam in summer. Finally, the spatial patterns of the EDH first mode in the SCS present a monopolar structure with the strong loading in northern SCS.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Exploring Multiple-Incidence Information in Deep Learning Schemes for
           Inverse Scattering Problems

    • Free pre-print version: Loading...

      Authors: Zhun Wei;
      Pages: 10876 - 10884
      Abstract: Recently, many successes have been witnessed in the field of inverse scattering problems (ISPs) with deep learning schemes (DLSs). However, most of the studies focus on the spatial characteristics of interested targets, and little attentions are paid to the information from multiple incidences that can be treated as temporal information measured in a time series. In this work, a multiple-incidence framework (MIF) is introduced by incorporating the information from multiple incidences into an extra dimension of data space, helping to enrich physical knowledge in DLSs. A 3-D convolutional neural network (CNN) structure is further introduced to explore cross-frame information of the data space, which enables simultaneous utilizations of multiple-incidence information. The proposed MIF can be easily adapted into previous DLSs in the literatures, where two widely used DLSs including back-propagation scheme (BPS) and dominant current scheme (DCS) are used to demonstrate the advantages of the proposed framework. It is shown by extensive numerical and experimental examples that MIF enables consistent improvements for BPS and DCS. It is expected that the proposed MIF will also find its applications in real-time dynamic microwave imaging and multiple-frequency imaging by effectively using physical knowledge from temporal and frequency measurements, respectively.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Geodesic Path Computation on Connected Trimmed Surfaces

    • Free pre-print version: Loading...

      Authors: Mounes Eslami;Vahid Mohtashami;
      Pages: 10885 - 10893
      Abstract: Creeping waves considerably contribute to the total high-frequency electromagnetic field in the shadow region. These waves propagate along surface geodesic paths. To trace them, geodesic differential equations have to be solved, which require special care in the case of connected trimmed surfaces. In this article, an algorithm is proposed to compute geodesic path transition across connected trimmed surfaces. The formulation includes efficient boundary recognition as well as accurately initializing geodesic equations on the next trimmed surface. For boundary recognition, inscribed or peripheral polygons are constructed to estimate the boundary and to effectively initialize numerical methods of quadratic convergence to determine the exact exit point. To get the initial point and initial direction on the parametric domain of the next trimmed surface, two optimization problems are efficiently solved. The proposed algorithm is applicable even if first/second-order surface discontinuity is encountered during the transition. The proposed method is validated on canonical surfaces and nonuniform rational B-spline (NURBS) surfaces for various trimming curves. Accurate computation of geodesic paths is observed. Furthermore, the far-field radiation pattern of a monopole antenna mounted on a sphere, a cylinder, and an ellipsoid is obtained and confirmed by numerical electromagnetic software.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An Efficient Method for Calculating the Doppler Spectrum of an Arbitrarily
           Shaped Object in Uniform Motion

    • Free pre-print version: Loading...

      Authors: Hongyun Deng;Gaobiao Xiao;Guomin Liu;
      Pages: 10894 - 10902
      Abstract: In the article, an efficient numerical method for calculating the spectrum of the scattering fields of an arbitrarily shaped object in uniform motion is proposed. This method relies on the frame hopping technique stemming from the special theory of relativity (STR). Firstly, the incident monochromatic plane wave is transformed to the comoving inertial frame in which the object is stationary. Next, the scattering fields of the moving object at the sampling time points are obtained in the comoving frame by solving the electromagnetic (EM) scattering problem with the conventional numerical method in the frequency domain. Then, the spectrum of the scattering fields in the frame in which the observer remains stationary is obtained using the discrete Fourier transform (DFT). The asymptotic expressions for the scattering fields when the moving object is far away from the observation point are derived, by applying which the computation efficiency could be greatly improved.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Channel Measurements and Modeling for Low Terahertz Communications in an
           Aircraft Cabin

    • Free pre-print version: Loading...

      Authors: Tobias Doeker;Johannes M. Eckhardt;Thomas Kürner;
      Pages: 10903 - 10916
      Abstract: The low terahertz band (0.1–1 THz) offers very high data rates for novel mobile applications and constitutes a promising candidate to meet the requirements in aviation, enabling future wireless in-flight entertainment (IFE) systems. An extensive knowledge of the propagation effects in the radio channel in complex scenarios is a prerequisite to successfully design a communication system. This article presents a measurement campaign in a real aircraft investigating the radio channel at 300 GHz for different deployments of a wireless IFE system. The propagation effects as well as temporal and spatial channel characteristics are analyzed for likely communication links between an access point and a user equipment (UE). In the same way, interference links between two UEs are studied, reporting transmission and reflection losses for various components of the aircraft. A deterministic and geometry-based channel model is derived and extended to cover the effect of human blockage that suggests an integration of the access point into the passenger service unit. The measurement and realistic path loss models can be used in further link and system level simulations and contribute to the design of future IFE systems.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A General Approach for Determining the Irradiance Distribution of EM Waves
           Propagating Through Random Media

    • Free pre-print version: Loading...

      Authors: Yousef M. Shishter;Rupert Young;Falah H. Ali;
      Pages: 10917 - 10924
      Abstract: The derivation of the probability density of irradiance for the received electromagnetic wave propagating through random inhomogeneities has applications in many diverse fields, such as optical wireless communications, radar, and imaging systems, to name few. The conventional approach in this regard is to combine distribution models, with each being found valid under different conditions, in a modulation process, e.g., the extended Rytov theory. However, in these techniques, the nature of the physical processes responsible for the randomness is not considered directly. Moreover, it is not clear how the model parameters are related to the physical environment. Recent research studies found that in random media, such as underwater, the exact physical processes in effect can significantly alter the distribution of the received signal intensity. In this article, a novel intensity distribution model is derived based on Rytov theory of propagation through weak turbulence. The physical parameters of the medium are directly included into the model parameters. Therefore, the resultant model is general enough to describe different physical environments. The utility of the model is validated by studying the effect of the medium parameters on the distribution through simulations.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Subspace-Rytov Approximation Inversion Method for Inverse Scattering
           Problems

    • Free pre-print version: Loading...

      Authors: Tiantian Yin;Li Pan;Xudong Chen;
      Pages: 10925 - 10935
      Abstract: In this article, we propose a novel non-iterative method, viz., the subspace-Rytov approximation (SRA) method, to solve inverse scattering problems. This method improves the inversion results of the Rytov approximation (RA) by retaining the integral term neglected therein. The evaluation of this integral involves two approximations. The integrand is approximated with its major part that results from the major induced current and is calculated by the subspace method. The integration on the whole space is approximated by an integration on a finite domain by truncation. Tests with both synthetic data and measured data show that the SRA method outperforms the RA inversion method and the Born approximation (BA) inversion method, and that the SRA outperforms the modified BA (MBA) method in accuracy for relatively large scatterers.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A 3-D Space-Time-Frequency Non-Stationary Model for Low-Altitude UAV
           mmWave and Massive MIMO Aerial Fading Channels

    • Free pre-print version: Loading...

      Authors: Jinpeng Xu;Xiang Cheng;Lin Bai;
      Pages: 10936 - 10950
      Abstract: In this article, a 3-D geometry-based stochastic model (GBSM) is proposed for millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) unmanned aerial vehicle (UAV) channels. The proposed model is the first mmWave massive MIMO UAV two-cylinder GBSM that enables to jointly model the channel space-time-frequency non-stationarity by a novel variable parameter-based method. In this novel method, key parameters of UAV channels are assumed to vary in space, time, and frequency domains, and the effect of the unique UAV-related parameters is further taken into account, such as the UAV’s altitude, velocity, and moving directions. Based on the proposed model, some statistical properties are derived, including the time-variant transfer function (TVTF), space-time-frequency correlation function (STF-CF), Doppler power spectral density (PSD), and the standard deviation of Doppler frequency on antenna arrays. Simulation results show that the channel non-stationarity in space, time, and frequency domains can be captured, and the aforementioned UAV channel-related parameters have a great impact on channel statistics. Finally, the utility of the proposed model is validated by the excellent agreement between simulation results and measurements.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Accurate Direction–of–Arrival Estimation Method Based on Space–Time
           Modulated Metasurface

    • Free pre-print version: Loading...

      Authors: Xinyu Fang;Mengmeng Li;Juzheng Han;Davide Ramaccia;Alessandro Toscano;Filiberto Bilotti;Dazhi Ding;
      Pages: 10951 - 10964
      Abstract: A metasurface (MTS)-based direction of arrival (DoA) estimation method is presented. The method exploits the properties of space–time modulated reflective metasurfaces to estimate in real-time the impinging angle of an illuminating monochromatic plane wave. The approach makes use of the amplitude unbalance of the received fields at broadside at the frequencies of the two first-order harmonics generated by the interaction between the incident plane wave and the modulated metasurface. Here, we first describe analytically how to generate the desired higher order harmonics in the reflected spectrum and how to realize the breaking of the spatial symmetry of each order harmonic scattering pattern. Then, the 1-D omnidirectional incident angle can be analytically computed using +1st- and −1st-order harmonics. The approach is also extended to 2-D DoA estimation by using two orthogonally arranged 1-D DoA modulation arrays. The accuracy of 1-D DoA estimation is verified through full-wave numerical simulations. Compared to conventional DoA estimation methods, the proposed approach simplifies the computation and hardware complexity, ensuring at the same time estimation accuracy. The proposed method may have potential applications in wireless communications, target recognition, and identification.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Millimeter-Wave Imaging Using a Rotating Dynamic Antenna Array and Noise
           Illumination

    • Free pre-print version: Loading...

      Authors: Daniel Chen;Stavros Vakalis;Jeffrey A. Nanzer;
      Pages: 10965 - 10973
      Abstract: We present a novel approach to millimeter-wave imaging that combines a new dynamic antenna array concept with active illumination by means of noise signals and interferometric image formation. The concept is based on a sparse linear array of receiving antennas that is dynamically rotated about its centroid, combined with three noise transmitters that illuminate the scene. Cross-correlations of the scattered signals received by individual array elements provide spatial frequency samples of the scene, from which the scene can be reconstructed via inverse Fourier transform. As the spatial frequency sampled by an antenna pair is dependent on the antenna baseline vector, dynamic rotation of the linear array generates sampling curves in the spatial frequency domain, providing a denser sampling function and a more accurate scene reconstruction. While traditional static interferometric imaging arrays utilize nearly an order of magnitude fewer antenna elements than phased arrays, our dynamic array concept relies only on a sparse linear array, further reducing the number of hardware elements required. We discuss the design of a 38 GHz dynamic antenna array imaging system and present measurements of multiple reflecting objects.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Hybrid OTA Chamber for Multidirectional Testing of Wireless Devices: Plane
           Wave Spectrum Generator Design and Experimental Demonstration

    • Free pre-print version: Loading...

      Authors: Oleg A. Iupikov;Pavlo S. Krasov;Andrés Alayón Glazunov;Rob Maaskant;Jonas Fridén;Marianna V. Ivashina;
      Pages: 10974 - 10987
      Abstract: This article investigates practical implementation aspects of a novel hybrid chamber concept that has been recently introduced for over-the-air (OTA) testing of wireless devices. The chamber allows to synthesize a spectrum of plane waves (PWs) incident on a device under test (DUT) from a wide range of angles of arrival (AoAs) through exploiting multiple field scattering inside the overmoded waveguide (WG) chamber. An optimal design approach for the plane wave spectrum generator (PWSG) array inside the chamber is presented considering: 1) array antenna impedance matching for the desired test zone (TZ) quality and AoAs’ range; 2) an operational frequency bandwidth of the test environment and an instantaneous signal bandwidth; and 3) the impact of PWSG excitation errors. A robust linearly constrained minimum variance (LCMV) beamformer is formulated to realize the desired test environment over a wide frequency band, while accounting for the varying number of the WG propagating modes as excited by PWSG array. Numerical simulations and measurements with the first prototype of the hybrid chamber for FR1 frequency band (~3.5 GHz) are presented. This prototype includes a ${7times 7}$ bowtie antenna element PWSG array, a 1.00 m $times1.25$ m $times1.75$ m metal WG chamber, an off-line optimal array beamforming setup, and a planar scanner for TZ characterization.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Tolerance Optimization of Antenna Structures by Means of Response Feature
           Surrogates

    • Free pre-print version: Loading...

      Authors: Slawomir Koziel;Anna Pietrenko-Dabrowska;
      Pages: 10988 - 10997
      Abstract: Fabrication tolerances and other types of uncertainties, e.g., the lack of precise knowledge of material parameters, have detrimental effects on the electrical and field performance of antenna systems. In the case of input characteristics, these are particularly noticeable for narrowband and multiband antennas where deviations of geometry parameters from their nominal values lead to frequency shifts of the operating frequency bands. Improving design robustness is therefore important yet challenging. On the one hand, it is numerically demanding as it involves uncertainty quantification (UQ), in particular, estimation and improvement of appropriately defined statistical performance metrics. On the other hand, it has to be carried out at the level of full-wave electromagnetic (EM) simulation models, which incurs considerable computational expenses. Executing UQ tasks at practically acceptable costs can be realized using surrogate modeling methods; however, the construction of reliable metamodels is hindered by the curse of dimensionality. This article proposes a novel approach to the robust design of antenna structures, where the task is formulated to increase the maximum values of parameter deviations for which 100% fabrication yield is ensured. Low cost of the optimization process is enabled by incorporating feature-based regression models for rapid yield estimation, as well as the employment of the trust-region framework for adaptive adjustment of design relocation but also as a convergence safeguard. Our methodology is validated using three microstrip antennas, including two dual-band and a triple-band structure.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Plane Spiral OAM Mode-Group Orthogonal Multiplexing Communication Using
           Partial Arc Sampling Receiving Scheme

    • Free pre-print version: Loading...

      Authors: Xiaowen Xiong;Shilie Zheng;Yuqi Chen;Zelin Zhu;Xiaonan Hui;Xianbin Yu;Xiaofeng Jin;Wei E. I. Sha;Xianmin Zhang;
      Pages: 10998 - 11008
      Abstract: A variety of novel orbital angular momentum (OAM)-based communication or sensing systems have attracted much attention over the past decade, the superiority is brought about by nothing other than its orthogonality or vorticity. Plane spiral OAM (PSOAM) mode-group (MG) technique as a reconfigurable beamforming method can be used for building a multiple-in-multiple-out (MIMO) system to achieve the reduction in subchannel correlation, which benefits from the spiral phase distribution within the mainlobe. However, the demultiplexing process still depends on the MIMO algorithm, in which the receiver complexity is same as the conventional MIMO systems. In this article, a PSOAM MG orthogonal multiplexing communication link at the X-band using partial arc sampling receiving (PASR) scheme has been demonstrated experimentally. The MG channels have a good isolation of about 15 dB, and the existing performance can ensure the reliable 16-QAM wireless transmission. Besides, a real-time dual-channel video transmission experiment has been carried out to verify the channel isolation caused by MG’s orthogonality intuitively. More importantly, the demultiplexing procedure using the PASR scheme can be implemented by simple analog phase shifting operation with a lower receiver complexity compared with the conventional MIMO systems.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Microwave Subsurface Imaging Method by Incorporating Radar and Tomographic
           Approaches

    • Free pre-print version: Loading...

      Authors: Shuto Takahashi;Katsuyoshi Suzuki;Takahiro Hanabusa;Shouhei Kidera;
      Pages: 11009 - 11023
      Abstract: Due to its high resolution and deep penetration depth, microwave ultrawideband radar is a promising tool for the non-destructive testing (NDT) of transportation infrastructure. Microwave radiation can also be used to reconstruct the dielectric properties of objects and therefore can be used to detect an air cavity or metallic rust in concrete. We used contrast source inversion (CSI) as one of the most promising inverse scattering schemes. To resolve the observation domain limitations of NDT, radar imaging method, also known as range points migration (RPM) method, was first incorporated into the inverse scattering algorithm based on CSI as a region of interest (ROI) estimator, which substantially improves the accuracy of complex permittivity reconstruction. In addition, the ROI optimizing scheme based on the CSI cost function is used to enhance ROI accuracy. The effectiveness of the proposed methods is validated via finite-difference time-domain (FDTD)-based numerical simulation, which assumes typical NDT model.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Geometry-Based UAV MIMO Channel Modeling and Pattern Optimization for
           Multimode Antennas

    • Free pre-print version: Loading...

      Authors: Nils Lennart Johannsen;Sami Alkubti Almasri;Peter Adam Hoeher;
      Pages: 11024 - 11032
      Abstract: Improving safety is of general interest in aviation. Flight transponders used in collision avoidance systems advise pilots with information of potential collisions and avoidance resolutions. Some transponders are capable of transmitting the instantaneous position of the vehicle which might be turned off. To prevent autonomous flights from collisions, the transponder signals shall be used to estimate the direction-of-arrival (DoA). Recently, multimode antennas have been investigated for communication and localization purposes. Multimode antennas provide several orthogonal ports on a single radiator surface. This leads to a reduction of space and weight, which is of interest in airborne applications. To perform DoA estimation as well as communication, a suitable channel model is required. In this contribution, a channel model fulfilling the requirements for both multiple-input multiple-output (MIMO) communication and DoA estimation is proposed. This channel model relies on the manifold matrix representation of the UAV under consideration. The derived description of a manifold matrix for the UAV use-case is used for an optimization to achieve a close to omnidirectional radiation pattern. Therefore, different optimization functions are derived and their performance is compared. The results of the optimization using the calculated manifold matrix are verified by measurements taken in an antenna measurement chamber.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Antenna Optimization for WBAN Based on Spherical Wave Functions
           De-Embedding

    • Free pre-print version: Loading...

      Authors: Lukas Berkelmann;Hendrik Jäschke;Leonardo Mörlein;Lukas Grundmann;Dirk Manteuffel;
      Pages: 11033 - 11044
      Abstract: Antennas for wireless body area networks (WBANs) need to be modeled with adapted methods because the coupling with the body tissue does not allow for a clear separation between antenna and channel. Especially for dynamically varying on-body channels due to changing body poses, e.g., with head-worn antennas, modeling is challenging and design goals for optimal antennas are difficult to determine. Therefore, in this article, the modeling of WBAN channels using spherical wave functions (SWFs) is utilized for antenna de-embedding and for deriving optimal antenna characteristics that maximize the transmission coefficient for the respective channel. It is evaluated how typical factors influencing WBAN channels (different body anatomies, body postures, and varying positions of the communication nodes) can be modeled statistically with SWF. An optimized antenna design is developed based on the derived optimization method, specifically adapted to the channel of on-body links with eye-wear applications. The results with the optimized antenna are compared to other standard antenna designs and validated against measurements.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Non-Line-of-Sight Wireless Indoor Localization System Using
           Custom-Designed Radio Relay and Uniform Circular Array

    • Free pre-print version: Loading...

      Authors: Kaikai Liu;Zengshan Tian;Ze Li;Xiaoyu Wan;
      Pages: 11045 - 11058
      Abstract: Indoor localization using WiFi signals, though getting studied for many years, is not adopted extensively in real indoor environments yet. One possible impediment is that many prior systems perform worse in non-line-of-sight (NLoS) indoor scenarios than in line-of-sight (LoS) scenarios or even fail to work. Nevertheless, realizing localization in both LoS and NLoS scenarios is indispensable for a viable system working in indoor environments. Since existing state-of-the-art solutions mainly aim to localize a target in LoS indoor scenarios, we present a system that uses multipath channel parameters to achieve localization with a single AP in indoor NLoS scenarios. The proposed introduces deployable and simple custom-designed radio relays to assist localization, which can receive signals from the target and forward them to the AP in NLoS scenarios. Field trials conducted in a real NLoS scenario show that our system achieves a median 3-D localization accuracy of 86 cm with a uniform circular array (UCA) in most NLoS conditions, i.e., the direct path from a target to AP is not completely blocked. More importantly, even if in a challenging NLoS condition, i.e., the direct path does not exist, our system can still achieve a median 2-D localization accuracy of 85 cm.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Nonlinear Model Compression Scheme Based on Variational Autoencoder for
           Microwave Data Inversion

    • Free pre-print version: Loading...

      Authors: Rui Guo;Zhichao Lin;Maokun Li;Fan Yang;Shenheng Xu;Aria Abubakar;
      Pages: 11059 - 11069
      Abstract: We present an inversion algorithm with a deep-learning-based model compression scheme. Models are described with latent parameters of a trained variational autoencoder (VAE) neural network. Given observed data, latent parameters are inverted by minimizing the data misfit cost function using the Gauss–Newton method. This inversion algorithm is tested using both synthetic and experimental datasets. We achieve a 0.87% compression rate while maintaining high-quality reconstruction. The deep neural network renders nonlinear model compression, which largely reduces the number of unknowns; hence, it has higher computational efficiency. Furthermore, various prior knowledge that is difficult to describe with rigorous forms can be incorporated into inversion through training the neural network, which mitigates the ill-posedness of the inverse problem.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Whole-Body Averaged Absorbed Power in Insects Exposed to Far-Field Radio
           Frequency Electromagnetic Fields

    • Free pre-print version: Loading...

      Authors: Hanne Herssens;David Toribio;Eline De Borre;Arno Thielens;
      Pages: 11070 - 11078
      Abstract: Insects are exposed to environmental radio frequency electromagnetic fields (RF-EMFs), which are partially absorbed by their body. This absorption is currently unknown for most insect types. Therefore, numerical simulations were performed to study the far-field absorption of RF-EMFs by different insect types at the frequencies between 2 and 120 GHz, which are (expected to be) used in (future) wireless communication. The simulations were done using anatomically accurate as well as spheroid models of the insects. The maximum absorbed power, which ranged from 7.55 to 389 nW for an incident electric field strength of 1 V/m for the studied insect types, was obtained at wavelengths comparable to the insects’ size. We created a log-linear model that can estimate absorbed power in insects with an average relative error of $ < 43%$ between 6 and 120 GHz using only the insects’ volume and the frequency as an input using the simulation results. In addition, our simulations showed a very high correlation ( $r> 0.95$ ) between the absorbed power predicted with anatomically accurate insect models and those predicted with spheroid models at the frequencies between 6 and 24 GHz. This suggests that such models could be used to evaluate the RF-EMF exposure of insects in future studies.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Spoof Surface Plasmon Polariton Antenna With Dual-Band Endfire Gain and
           Flexible Small Frequency Ratio

    • Free pre-print version: Loading...

      Authors: Hongxin Zhao;Jinlun Li;Qiuyi Zhang;Shunli Li;Xiaoxing Yin;
      Pages: 11079 - 11084
      Abstract: A spoof surface plasmon polariton (SSPP) antenna with dual-band endfire gain and small frequency ratio (FR) is presented. It uses an asymmetric structure to support two independent surface waves with different nonlinear phase constants. Due to the different phases of the superposed $E$ -field at the terminal of the proposed structure, dual-band endfire gains and endfire radiation null are achieved. The odd- and even-mode feedings, providing additional phase differences, are also investigated. Three prototypes, with FRs of 1.06, 1.11, and 1.5, are designed, simulated, and measured, respectively. All results validate the mechanism and demonstrate that the FR of the proposed antenna can be achieved easily in the range of 1.06–1.5 by choosing different unit cells and feeding modes. Moreover, the measured endfire out-of-band gain suppression, over 17 dB, presents a good directional interference inhibition. This small-FR endfire antenna shows a broad prospect for band coverage and directional noise inhibition with very close operating frequencies.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Broadband Circularly Polarized Magnetoelectric Dipole Antenna by Loading
           Parasitic Loop

    • Free pre-print version: Loading...

      Authors: Kang Ding;Yujian Li;Yanjie Wu;
      Pages: 11085 - 11090
      Abstract: A broadband circularly polarized (CP) magnetoelectric (ME) dipole antenna loaded with parasitic loop is presented in this communication. The proposed ME dipole antenna is fed through the slot-coupled feeding method, in which a microstrip line is used to couple the energy to the antenna by the slot etched on the ground plane. By introducing a parasitic loop coplanar with the horizontal patch, extra CP modes are generated due to the coupling with the radiation patch. Combining with the original CP mode, the simulated 3 dB axial-ratio (AR) bandwidth is enhanced from 12.2% to 45.8% with an increment of 33.6%. The measured results show that the 10 dB impedance bandwidth is 55.3% (3.4–6.0 GHz) and the 3 dB AR bandwidth is 42.1% (3.62–5.55 GHz). Moreover, the proposed antenna owns flat gain and stable unidirectional radiation patterns within the designated frequency band.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Fabry–Perot Conical Beam Antenna With Multi-Polarization
           Reconfigurable Capability

    • Free pre-print version: Loading...

      Authors: Junxiang Yang;Shi-Shan Qi;Wen Wu;Da-Gang Fang;
      Pages: 11091 - 11096
      Abstract: In this communication, a Fabry–Perot (FP) conical beam antenna with multipolarization reconfigurable capability is proposed. A single-layer partially reflective surface (PRS) with circular slots is designed for the prescribed flare angle determined by the height of the FP antenna and resonant frequency. A group of Vivaldi patches with a set of shorting vias around a common central axis on a printed circuit board (PCB) are used as the primary source, which is fed by nested coaxial waveguide. Vivaldi patches coupled with parallel baluns, which are connected to the internal coaxial waveguide, are used to produce a horizontally polarized conical beam. A vertically polarized conical beam can be obtained when the external coaxial waveguide is used to feed the Vivaldi patches. When circularly polarized conical beams are required, the internal and external coaxial waveguides need to be excited at the same time with the same amplitude and the proper phase difference. A prototype of the proposed FP conical beam antenna with multipolarization reconfigurable capability at 12 GHz is designed, fabricated, and measured to verify the concept. The measured results are in good agreement with the simulated ones. A maximum gain of $ge 12.8$ dBic is achieved with the proposed FP conical beam antenna for the two circular polarization states, with an axial ratio (AR) and impedance bandwidth (IBW) of $ge 16.7$ % and 8%, respectively. The maximum gain and IBW for the horizontal polarization (HP) and vertical polarization (VP) are $>13.2$ dBi and 9.2%, respectively.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Compact Tri-Band Filtering Antenna System for 5G Sub-6 GHz Applications

    • Free pre-print version: Loading...

      Authors: Zhu Duan;Shuo Shen;Geyi Wen;
      Pages: 11097 - 11102
      Abstract: This communication presents a novel compact tri-band filtering antenna for 5G Sub-6 GHz n41 (2.515–2.675 GHz), n78 (3.4–3.6 GHz), and n79 (4.8–5 GHz) applications. The antenna consists of a central dual-band element and four single-band elements placed around. Simulated results show that the tri-band filtering antenna has an impedance bandwidth ( $vert S_{11}vert < -10$ dB) of 6.6% (2.51–2.68 GHz), 6.3% (3.39–3.61 GHz), and 5.5% (4.73–5 GHz), covering Chinese 5G Sub-6 GHz band. The distance between single-band elements along both the x-axis and y-axis is $0.31lambda _{0}$ ( $lambda _{0}$ is the free-space wavelength of the center frequency at the lowest band), realizing a compact structure of $0.95lambda _{0} times 0.95lambda _{0} times 0.2lambda _{0}$ . Since this tightly spaced structure will easily cause strong coupling, additional filtering structure is added, achieving high isolation over 47 dB between the central and the peripheral elements. The final antenna realizes stable gain in all three frequency bands, showing satisfactory in-band average radiation efficiency and high out-of-band gain-suppression level, making it suitable for 5G Sub-6 GHz wireless communication applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Reconfigurable Half-Mode SIW Antenna Using Uniaxial Field Programmable
           Microwave Substrate Structure

    • Free pre-print version: Loading...

      Authors: David René-Loxq;Olivier Lafond;Mohamed Himdi;Langis Roy;Farhan Ghaffar;
      Pages: 11103 - 11108
      Abstract: This communication presents the design and implementation of a beam steerable leaky wave antenna (LWA) based on integrated electronic devices (varactor diodes). The design uses a half-mode substrate-integrated waveguide (HMSIW) where the short-circuited wall or PEC boundary is realized with field programmable microwave substrate (FPMS)-based unit cells. By virtue of placing integrated varactor diodes in these unit cells, the wavenumber and the phase shift of the propagating signal can be controlled. This allows a beam steering of 25° for a fixed center frequency. Furthermore, control of the varactor bias voltages allows a fixed beam direction over a wide frequency bandwidth. An excellent agreement can be observed between the simulated and measured results, validating the first ever FPMS-based reconfigurable antenna design.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A High-Gain Endfire Periodic Leaky-Wave Antenna Using DSPSL-Based Rhombic
           Element

    • Free pre-print version: Loading...

      Authors: Kuang Wang;Yuanxin Li;Zhixi Liang;Shao Yong Zheng;Yunliang Long;
      Pages: 11109 - 11114
      Abstract: An endfire periodic leaky-wave antenna (LWA) with high gain is presented in this communication, which consists of a series of rhombic elements based on double-sided parallel stripline (DSPSL). The endfire mechanism of the proposed antenna is illustrated by the phase difference of the far field of each arm in the rhombic element. Meanwhile, a tradeoff between the tilted angle $theta _{0}$ and the width $w$ is found, which assures an optimum transverse aperture for achieving high-gain endfire radiation. Moreover, the improved Hansen–Woodyard (IHW) condition is applied to predict the optimum endfire phase constant. Finally, a prototype is fabricated and tested. The maximum endfire gain of 19.8 dBi is measured at 11.4 GHz, which is close to the simulated and predicted results. The proposed periodic rhombic antenna provides more choice for the modern communication system.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Dual-Wideband Cavity-Backed Antenna by Using Waveguide Transition and
           Short-Ended Groove Loading

    • Free pre-print version: Loading...

      Authors: Jing-Yi Zhang;Jin-Dong Zhang;Yingrui Yu;Yan-Ting Liu;Wen Wu;Da-Gang Fang;
      Pages: 11115 - 11120
      Abstract: A novel scheme is presented to control the frequency response on an open-ended waveguide antenna. A groove is loaded in the waveguide that is used to independently control the frequency response of the antenna without affecting the radiation pattern, and a transition is used to provide additional control. A dual-wideband antenna is taken as an example to verify the effectiveness of the scheme. To demonstrate the idea, an antenna element and its $2times2$ array were designed, fabricated, and measured. Reasonable agreement between the measured and simulated results has been observed. The measured 10 dB impedance bandwidths of the lower and upper bands of the proposed element are achieved to be more than 22.2% and 14.2%, respectively, fully covering the 26/28 GHz band (24.25–29.5 GHz) and 39 GHz (37–40 GHz) band.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Analysis and Design of an Ultrawideband Dual-Polarized Antenna for IBFD
           Applications

    • Free pre-print version: Loading...

      Authors: Son Xuat Ta;Nghia Nguyen-Trong;
      Pages: 11121 - 11126
      Abstract: This communication investigates design requirements for a class of dual-polarized in-band full-duplex (IBFD) antennas utilizing a symmetry of structures and a differential-feeding scheme. The analysis reveals that, to achieve zero coupling between two ports, the out-of-phase power divider (PD) does not need to have perfect isolation and perfect matching at the two output ports. A more relaxed set of requirements for the PD is derived for the first time. Based on this, an ultra-wideband cross-shaped Vivaldi antenna is designed for IBFD applications with very high isolation. The measured 10 dB return loss bandwidth is 1.26–8.0 GHz (145.5%), while the measured port-to-port isolation is >42 dB at 1.26–4.7 GHz (115.4%) and >34 dB within the whole operational bandwidth.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Wideband Folded Dipole Antenna With Stable Radiation Patterns Under
           Multiresonant Modes

    • Free pre-print version: Loading...

      Authors: Yuqi Wang;Zhipeng Hu;Quan Xue;
      Pages: 11127 - 11131
      Abstract: A novel wideband folded dipole antenna (FDA) with stable radiation patterns under multiresonant modes is proposed in this communication. First, by lengthening and widening the driven strip of an FDA, the input resistance of its 1st- and 3rd-order modes declines significantly. Second, the driven and non-driven strips are further widened at a fixed ratio to achieve better impedance matching. Third, a pair of open-slot loops (OSLs) is advisably added to compress the resonant frequency of the 5th-order mode close to that of the 3rd-order mode for bandwidth improvement. Finally, a prototype is fabricated to provide experimental verification of the idea, and measured results show that the proposed FDA has a bandwidth of about 82% from 1.72 to 4.10 GHz, which exhibits a good agreement between measurement and simulation. In particular, the proposed FDA obtains stable radiation patterns in the entire operating band.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Dual-Band Transmitarray Antenna Employing Ultra-Thin,
           Polarization-Rotating Spatial Phase Shifters

    • Free pre-print version: Loading...

      Authors: Mohammad Mahdi Honari;Konstantinos Mavrakakis;Hung Luyen;John H. Booske;Nader Behdad;
      Pages: 11132 - 11137
      Abstract: We present a dual-band transmitarray (TA) comprising ultrathin polarization-rotating (PR) spatial phase shifters. The PR elements provide $+ 90^circ $ and $- 90^circ $ polarization rotation independently in two different frequency bands, used as dual-band 1-bit spatial phase shifters. Independent polarization rotation in the two operating frequency bands is realized by interleaving high-band and low-band features that include dipoles, strips, and slots printed on three metallic layers with ultrathin interlayer spacings. The concept is generally applicable to any frequency band where TAs are practical. To illustrate the concept, we simulated and tuned a PR unit cell to achieve 1-bit phase shifts in two operating frequency bands at X- and Ku-bands, with center frequencies at 9.5 and 14.5 GHz, respectively. Subsequently, a dual-band TA was designed using the proposed unit cell to provide beam collimation at broadside directions at both operating frequency bands. The proposed ultrathin spatial phase shifter results in a TA with an overall thickness of $0.07lambda _{LB}$ , where $lambda _{LB}$ is the wavelength at the center frequency of the lower band. Measurement results of a fabricated prototype of the TA show maximum gains of 25.2 and 26.2 dBi as well as 3 dB gain bandwidths of 26% and 6.2% for the lower and higher bands, respectively.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Compact High Gain Omnidirectional Horizontally Polarized Antenna Array
           Utilizing an Aperture With Uniform Field Distribution

    • Free pre-print version: Loading...

      Authors: Zhenchuan Liang;Lijuan Huang;Wentao Xu;Yeshun Peng;Jianying Wang;Han Zhang;
      Pages: 11138 - 11142
      Abstract: A compact high gain omnidirectional horizontally polarized (OHP) antenna array is proposed in this communication. The theoretical calculations prove that a slender aperture with uniform field distribution can achieve OHP radiation with high directivity. The rectangular patch antenna operating in TM10 mode is employed to obtain an element with the specific field distribution. To extend the electrical length of the aperture, the element is elongated, and four collinear elements are integrated as an array without any redundant structures. Benefitted from the reasonable electric field distribution and concise configuration, the aperture efficiency is significantly improved. Therefore, the proposed antenna can achieve high gain OHP radiation in a compact size. The overall dimension of the antenna array is $4.62lambda times 0.22lambda times 0.07lambda $ ( $lambda $ is the free space wavelength at the center frequency). Measured results verify that the impedance bandwidth of the array covers 5.46–6.13 GHz with a relative bandwidth of 11.6%, a maximum realized gain of 11 dBi, and good omnidirectional characteristics with a gain variation of less than 3 dB in the entire operating bandwidth.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Simple Dual-Polarized Patch Antenna Array for Wi-Fi 6/6E Application

    • Free pre-print version: Loading...

      Authors: Xiaopeng Zhang;Dawei Zhou;Yue Li;Kunpeng Wei;Zhijun Zhang;
      Pages: 11143 - 11148
      Abstract: A simple, high gain, and dual-polarized patch antenna array for Wi-Fi 6/6E application is proposed in this communication. Different from the conventional feeding method, the patches are driven by coupling dipoles that are printed on the same board. The dipoles are specially designed to be T-shaped to adjust the impedance matching. Broadband covering both 5 and 6 GHz bands of Wi-Fi 6/6E is achieved. The feeding circuit is easily integrated on the board with only parallel dual line utilized. A prototype is fabricated and tested to validate the concept. The measured and simulated results are in good agreement. The measured bandwidth with $S_{11} < -10$ dB for two ports are 5.12–7.50 and 5.15–7.50 GHz with the isolation higher than 30 dB. Moreover, the measured gains are higher than 9.76 and 9.61 dBi for two ports over the operating band with a peak value of 12.05 dBi. The proposed antenna array shows great potential in the application of Wi-Fi mesh.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A 1-to-8 Fully Modular Stacked SIW Antenna Array for Millimeter-Wave
           Applications

    • Free pre-print version: Loading...

      Authors: Cleofás Segura-Gómez;Ángel Palomares-Caballero;Pablo Padilla;
      Pages: 11149 - 11154
      Abstract: This communication presents a vertically stacked substrate-integrated waveguide (SIW) antenna array that enables different array configurations with the minimum number of SIW layers. This achievement lies in the modular feature offered by the proposed design. Specifically, four distinct array configurations can be produced with only three different designs of SIW layers. Depending on the number of SIW layers employed in the stacked antenna, the directivity in the E-plane is modified. To obtain an equal and in-phase power distribution among the array elements, H- and E-plane corporate feeding networks are efficiently implemented in each array configuration. Array configurations of one, two, four, and eight radiating layers are offered by the proposed modular array, where each radiating layer is formed by eight H-plane horn antennas. The simulated directivity for the array configurations ranges from 15.8 to 23.8 dBi and the main beam direction remains fixed along the operating frequency range. The array design has been manufactured, and an agreement between simulated and measured results is observed. The measured impedance bandwidth in all the array configurations is from 35 to 41 GHz (15.79% bandwidth) with a reduction in the E-plane beamwidth as the number of radiating layers increases.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Transmitarray Antenna for Conical Beam Scanning

    • Free pre-print version: Loading...

      Authors: Anastasios Papathanasopoulos;Yahya Rahmat-Samii;
      Pages: 11155 - 11160
      Abstract: Conventional transmitarray antennas are designed to produce a directional pattern with the beam peak in a single direction when the feed is placed at a distinct location. A real-life application requiring conical beam scanning necessitates the development of antennas with patterns that sweep out a cone in space through successive excitation of feeds placed at multiple locations along the body of the revolution ring focus. In this communication, we propose transmitarrays as an antenna solution that can achieve the conical beam sweep. Compared to the previously reported transmitarrays, the development of an off-axis-fed transmitarray for conical beam scanning requires significant advancements regarding the synthesis and optimization of the off-axis-fed transmitarray. A novel synthesis algorithm is presented based on the optimization of the feed location and a modified transmitarray phase compensation. To validate the approach, an 18 cm transmitarray with a thickness of 0.8 cm operating at 13.4 GHz is designed, simulated, prototyped, and measured. Predictions obtained by full-wave simulations agree well with the measured results. The conical beam scanning capability of the transmitarray is demonstrated through measurements taken with the feed placed at five locations within the ring focus.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Circularly Polarized Double-Folded Transmitarray Antenna Based on
           Receiver-Transmitter Metasurface

    • Free pre-print version: Loading...

      Authors: Tang-Jing Li;Guang-Ming Wang;Hai-Peng Li;Hai-Sheng Hou;
      Pages: 11161 - 11166
      Abstract: In this communication, a circularly polarized (CP) double-folded transmitarray antenna (DFTA) is proposed and experimentally verified for the first time in the open literature. It is designed based on a receiver–transmitter metasurface (RTMS) and a polarization rotating (PR) metasurface (MS). A linearly polarized (LP) patch antenna is integrated on the RTMS instead of a horn antenna to feed the DFTA. Through double-folded reflecting, twice PR, LP wave receiving, CP wave transmitting, and transmission phase manipulating, the LP spherical wave from the feed is transformed into the high-gain pencil-shaped CP beam. The strategies innovatively break the restriction that the previous folded reflectarray (FRA) and folded transmitarray (FTA) antennas are only LP. Moreover, the double-folded design further reduces the antenna profile to about 1/4 of the focal length. The simulation and experiment results are in good agreement, which exhibits a peak gain of 21.8 dBic at 9.8 GHz and a maximum aperture efficiency of 40%. Meanwhile, the DFTA obtains a −1 dB gain bandwidth of 6% (9.6–10.2 GHz), in which the axial ratio is lower than 1.5 dB.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Single-Layer Broadband Ka-Band Reflectarray Using Novel Windmill
           Elements

    • Free pre-print version: Loading...

      Authors: Jianing Zhao;Cheng Fu;Hao Li;Fang Li;Xueyao Hu;
      Pages: 11167 - 11171
      Abstract: A single-layer novel windmill element is designed to broaden the bandwidth of reflectarray antenna (RA) in this communication. To obtain the enough phase range, a windmill ring patch and a circular ring patch are utilized to realize the multiresonant state. As a result, a linear phase shift curve which covers 473.6° phase range is achieved by optimizing the parameters. Based on that, a large proportion of phase shift curve keeps parallel from 27.5 to 42.5 GHz, it indicates the proposed element features broadband property. To this end, a single-layer offset-fed prototype with a square aperture of 80 mm $times80$ mm which is composed of 400 elements is designed, measured, and tested at Ka-band. Through detailed measurements, a peak gain of main beam is 27.86 dBi with an aperture efficiency of 51.7% has achieved at 37 GHz. The sidelobe level and cross-polarization are also lower than −17 and −25 dB, respectively. More importantly, the degradation of the peak gain from 27.5 to 40 GHz (35.71%) is less than 3 dB. The proposed antenna which features wide bandwidth with good radiation performance and simple structure will be suitable for 5G millimeter-wave communication.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Fuzzy Entropy for Frequency Diverse Array Beampattern Synthesis

    • Free pre-print version: Loading...

      Authors: Jiaang Ge;Junwei Xie;Bo Wang;Chushu Chen;
      Pages: 11172 - 11176
      Abstract: Frequency diverse array (FDA) can generate a range-angle-dependent beampattern due to the introduction of the tiny frequency offsets across array elements. However, the range-angle-coupled beampattern is detrimental to the estimation of the target parameter, and even the normal function of the FDA. In fact, the main purpose of the FDA beampattern synthesis is to achieve beampattern decoupling, mainlobe attenuation avoidance, and sidelobe suppression. Furthermore, these conditions can be summarized as the chaotic degree modulation of the beampattern. In this communication, the 2-D fuzzy entropy is first employed in the FDA beampattern synthesis. The proposed FDA can generate a dot-shaped beampattern with high fuzzy entropy in the near-target field and low fuzzy entropy in the far-target field. In addition, by introducing time-variant weights, the time modulation is suppressed in the fuzzy entropy-based FDA (FEBFDA). The results of the numerical simulation demonstrate the superiority of the proposed beampattern synthesis method.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • A Novel Dual-Band Shared-Aperture Antenna Based on Folded Reflectarray and
           Fabry–Perot Cavity

    • Free pre-print version: Loading...

      Authors: Zhen-Guo Liu;Ren-Jie Yin;Wei-Bing Lu;
      Pages: 11177 - 11182
      Abstract: This communication proposes a novel dual-band shared-aperture antenna hybridizing Fabry–Perot cavity antenna (FPCA) and folded reflectarray (FRA), which operates at both sub-6 GHz and millimeter-wave bands with a large frequency ratio of 1:4.6. This antenna is composed of two substrates, with metasurface printed on the upper substrate and reflector layer printed on the lower one. The metasurface works as partially reflective surface (PRS) of FPCA at the sub-6 GHz band while acts as polarization grid of FRA at the millimeter-waveband. Thus, the FPCA and the FRA are able to share the same aperture with high aperture reuse efficiency. A composite feed structure combining waveguide with microstrip patch antenna is used to feed at two bands, implementing shared-aperture feed. This antenna achieves high gains at two bands without complicated feeding networks. A prototype operating at 5.4 and 25 GHz bands is designed, fabricated, and measured to verify the idea.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • High Gain Wideband Circularly Polarized Microstrip Antenna Array

    • Free pre-print version: Loading...

      Authors: Anamika Verma;Mahima Arrawatia;Girish Kumar;
      Pages: 11183 - 11187
      Abstract: A wideband high gain circularly polarized microstrip antenna (CP MSA) array is presented in this communication. In the proposed CP MSA array, the elements are designed at 3.5 and 5.8 GHz, which are sequentially rotated to form a planar array. The array elements are fed using the $TM_{110}$ and $TM_{210}$ modes of a center CP MSA. This arrangement achieves an axial ratio (AR) bandwidth of 63.7% (3.25–6.29 GHz) and improves gain over a wide bandwidth. The peak gain of the array is 17.77 dBic with a 3-dB gain bandwidth of 53.9%. The center MSA of the array is fed using four orthogonal printed L-probes with quadrature phase difference. The proposed CP MSA array has an $ S_{11} leq -10$ dB bandwidth of 63.3% (3.32–6.4 GHz).
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Miniaturized Broadband Dual-Polarized Dipole Antenna Based on Multiple
           Resonances and its Array for Base-Station Applications

    • Free pre-print version: Loading...

      Authors: Wanchen Yang;Yongzheng Li;Quan Xue;Shaowei Liao;Wenquan Che;
      Pages: 11188 - 11193
      Abstract: A novel bandwidth enhancement method using loading multiple parasitic structures to realize broadband miniaturized antenna is proposed. Based on the proposed strategies, one miniaturized wideband dual-polarized dipole antenna covering LTE/CDMA/GSM bands (690–960 MHz) for base-station application is designed. The antenna consists of two folded bowtie-shaped dipoles fed with a pair of crossed baluns, and is further loaded on a ceramic block with high permittivity ( $varepsilon$ ) for miniaturization. A parasitical square loop is loaded for bandwidth enhancement at a lower frequency. In addition, four split rings with a small square loop are firstly adopted for antenna resonance tuning, the impedance bandwidth is thus improved effectively. The antenna size is only $0.18,times ,0.18,times , 0.22,,lambda _{0}$ at the center frequency. The measured result of the fabricated prototype exhibits a relatively large operation bandwidth of 32.73% (VSWR < 1.6) with stable radiation patterns and relatively flat broadside gains. Moreover, to verify the feasibility of the proposed miniaturized antenna element in the base-station application, an array of $2,times , 4$ is further designed. The measured results of the array indicate isolation over 20 dB with an impedance bandwidth of 32%. Due to the good performance and compact feature, the proposed miniaturized broadband antenna element can find large application potential in multiband wireless communication base stations.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Communication A Novel Systematic Design of High-Aperture-Efficiency 2D
           Beam-Scanning Liquid-Crystal Embedded Reflectarray Antenna for 6G FR3 and
           Radar Applications

    • Free pre-print version: Loading...

      Authors: Hogyeom Kim;Jongyeong Kim;Jungsuek Oh;
      Pages: 11194 - 11198
      Abstract: This communication presents a novel systematic design of a high-aperture-efficiency and 2-D beam-scanning nematic liquid-crystal (LC)-based reflectarray (LCRA) that operates in the sixth-generation (6G) midband (7–24 GHz). Despite a 260° phase range, the maximum aperture efficiency is 35.8% at an aperture dimension (F/D) ratio of 0.58, the highest aperture efficiency at the lowest F/D ratio among LCRAs designed to operate on the mmWave band. The proposed LC-based reflectarray unit cell (LC-RUC) has significantly low reflection loss compared to other LC-RUCs. Also, the bias topology of the proposed LC-RUC makes the LCRA capable of 2-D beam scanning. The beam-scanning range of the proposed LCRA is ±50° on the xoz plane and 0°–65° in the yoz plane at 9.55 GHz. A $2 times 2 $ patch array antenna is designed as the feed antenna to achieve a small F/D ratio system and ease of optimization. When designing the feed antenna, the number of elements or the element spacing is considered to achieve high feed efficiency. In addition, the fabricated planar feed antenna can be easily integrated with a 3-D printed jig in which the focal length can be adjusted for optimization. The lowest side lobe level (SLL) of the proposed LCRA is −15.5 dB.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Shared-Aperture Ka-Band Reflectarray and X-Band Phased Array for Broadband
           Inter-Satellite Communication

    • Free pre-print version: Loading...

      Authors: Yao Yao;Xian Qi Lin;Tao Qin;Yihong Su;Xinmi Yang;
      Pages: 11199 - 11204
      Abstract: In this communication, a dual-band shared-aperture reflectarray (RA) with a phased array is proposed for intersatellite links (ISLs). The Ka-band RA is integrated with an X-band phased array by a sharing mushroom patch structure. The high-frequency ratio allows the high-frequency RA and the low-frequency broadband phased array to operate independently to support high-speed communication of the geostationary orbit (GEO) relay nodes in the intersatellite network. To verify this concept, a prototype of the antenna is designed and fabricated, and its electrical performance is measured. The RA presents a peak gain of 30.1 dBi (28 GHz) and a 3 dB gain bandwidth of 11.4% (26.4–29.6 GHz). The phased array presents the peak gain of 21.7 dBi (9 GHz), and the relative bandwidth can reach 45.3% in the boresight direction. The scanning range can cover ±45°, and the H/E planes scan gain losses are less than 2.34 and 4.33 dB, respectively.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Polarization Selective Partial Reflective Decoupling Layers for Mutual
           Coupling Reduction of Two Closely Spaced Dual-Polarized Antennas

    • Free pre-print version: Loading...

      Authors: Ge Zhao;Ting Liu;Jiayue Jiang;Luyu Zhao;Guan-Long Huang;Wei Lin;
      Pages: 11205 - 11210
      Abstract: In this communication, two polarization selective partial reflective decoupling layers (PRDLs) are utilized to mitigate at least two kinds of mutual couplings between two closely spaced dual-polarized dipole antennas. The PRDL is a large-scale model of an actual dielectric board, obtained by arranging a large number of identical conducting obstacles in a regular two-dimensional pattern. The two PRDLs are designed at proper distances from the antenna aperture with well-engineered dielectric constants for two preset polarizations. Each layer is selective to only one polarization by appropriately designing the dimension of the unit cells. Consequently, the two dominant couplings between the two dual-polarized antennas are reduced significantly. The measured isolation between all ports of the two antennas are increased to more than 21 dB, while their reflection coefficients can still maintain in satisfactory status. The radiation patterns, total efficiencies, and envelop correlation coefficients of the proposed antenna, as well as its counterpart without any decoupling measures, are also obtained through measurement, showing significant and reasonable improvements, which further indicates that it has great potential to be extended and applied to 5G MIMO arrays in both base stations and wireless routers.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Tapered Resistive Sheets Loading to the FSS Absorber for the Wide-Angle
           Monostatic RCS Reduction Applications

    • Free pre-print version: Loading...

      Authors: Ze Huang;Zhinan Luo;Gengjiang Yao;Rui Li;Yong Zhao;Qiyang Cao;Yi Han;Ling Miao;Jianjun Jiang;
      Pages: 11211 - 11216
      Abstract: In this communication, wide-angle monostatic radar cross section (RCS) reduction of a metal plate is reported. The whole angular range (0°–90°) is divided into three parts according to the different dominant scattering mechanisms. Each dominant scattering mechanism is accurately identified and suppressed effectively. Frequency selective surface (FSS) absorber is employed to reduce the specular echo intensity within the first angular part. The tapered resistive sheets (TRSs) are loading as an edge termination to the metal layer and FSS layer, respectively, providing a slowly varying surface current to taper the transition between the free space and the targets. Significant RCS reduction in the rest two angular parts is achieved. Simulation results clearly show that more than 10 dB monostatic RCS reduction is realized within a wide angular range (0°–10° and 30°–85°) for the frequency band ranging from 1.3 to 2 GHz. Samples have been fabricated and measured in the anechoic chamber, and a remarkable agreement between the simulation and measurement is obtained. The effectiveness of the design is fully verified.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Backend-Balanced-Impedance Concept for Reverse Design of Ultra-Wideband
           Absorber

    • Free pre-print version: Loading...

      Authors: Zhaowang Cao;Haoran Li;Yi Wu;Gengjiang Yao;Yong Zhao;Ze Huang;Sai Guo;Ling Miao;Jianjun Jiang;
      Pages: 11217 - 11222
      Abstract: Wider absorption bandwidth is usually accompanied by more complex and difficult designs and more computational costs, which have become an important challenge in the field of electromagnetic scattering. In this communication, the backend-balanced-impedance (BBI) new design concept is put forward for the first time which considers the backplane as an impedance that can be designed to compensate for the impedance of a known absorber for expanding the absorption bandwidth. Based on the design concept, an ultra-wideband absorber derived from the known absorber is proposed simply and efficiently. The matched BBI for the known absorber is obtained and developed using reverse calculation. To explain the operating principle, a simple equivalent circuit (EC) model of the ultra-wideband absorber from the BBI is established. Furthermore, the electric field and surface loss distribution are systematically analyzed to demonstrate physical pictures of the BBI. The simulated and measured results show that the designed ultra-wideband absorber from the BBI can get an absorption band in the 0.87–9.28 GHz range (165.8%) for at least 10 dB of reflection reduction at the normal incidence with a thickness of only $0.0858lambda _{L} $ , where $lambda _{L} $ denotes the wavelength at the lowest operating frequency.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • The Applications of the Symmetric Layered Medium Green’s Function in
           Magnetic Field Integral Equation

    • Free pre-print version: Loading...

      Authors: Shuo Wang;Qiang Ren;Yi Ren;Xunwang Dang;Zhaoguo Hou;Hua Yan;Liangsheng Li;Hongcheng Yin;
      Pages: 11223 - 11228
      Abstract: A symmetry relation of the integral operators in a layered medium proved by the reciprocal theory can be applied to improve the accuracy of the magnetic-field integral equation (MFIE). Based on the symmetric layered medium Green’s function, the normal vector can be transferred into the inner integral to keep the field integral as the inner integral of the elements in the impedance matrix. When discretized by the divergence-conforming function, this field-extracted scheme shows better performance than the classic expression in accuracy. Meanwhile, this form of expression can be applied in the combined-field integral equation (CFIE). Several numerical results are provided to validate the formulation of the symmetry relations from the layered medium Green’s function to the impedance matrices and to reveal its advantages in enhancing the accuracy of the field-extracted form of MFIE.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Knowledge-Based Neural Network for Thinned Array Modeling With Active
           Element Patterns

    • Free pre-print version: Loading...

      Authors: Yang Hong;Wei Shao;Yan-He Lv;Bing-Zhong Wang;Lin Peng;Baojun Jiang;
      Pages: 11229 - 11234
      Abstract: To speed up the process for designing finite thinned arrays, an efficient artificial neural network (ANN) model considering mutual coupling effects is proposed in this communication. Array elements are divided into three categories based on the active element pattern (AEP) technique, and subarrays are constructed to extract the AEP of each category of elements as training samples. The proposed model including parallel ANN branches takes into account the mutual coupling between elements and avoids the calculation of the radiation pattern of the entire array. To improve modeling performance, furthermore, a prior knowledge input technique is used to reduce the complexity of the input–output relationship that an ANN has to learn. The existing knowledge is obtained by back propagation (BP) ANN modeling. Once the knowledge-based model is well trained, it is repeatedly called by the genetic algorithm (GA) for the optimal solution as a substitute for the full-wave simulation. Numerical examples of a U-shaped slot thinned array and a dual-layer patch thinned array are utilized to verify the efficiency of the proposed scheme.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Validation of HBF-Based MoM Approach to Solution of Radiation and
           Scattering Problems on Microwave Antennas With Linear Elements

    • Free pre-print version: Loading...

      Authors: Faik G. Bogdanov;Lily Svanidze;Irina Chochia;Roman Jobava;
      Pages: 11235 - 11239
      Abstract: A recently proposed method of moment (MoM)-based approach is extended to efficiently solve broadband radiation and scattering problems on wire and mixed geometries. This approach is based on expanding the total current on a conducting structure at any desired frequency in terms of entire domain hyper basis functions (HBFs), calculated at only one frequency. The developed approach is validated by comparing the characteristics of canonical microwave antennas with those obtained by direct MoM and characteristic mode analysis (CMA).
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • An Analytical Propagation Model Based on Dyadic Green’s Functions for
           TTE Communications in an Arbitrary Stratified Soil

    • Free pre-print version: Loading...

      Authors: Bruno P. Chaves;Adoniran Judson Braga;
      Pages: 11240 - 11245
      Abstract: In this work, we present a novel analytical model for the magnetic field in through-the-Earth (TTE) communications. The modeling approach is based on dyadic Green’s functions to compute impressed and scattered fields in a multilayered structure. Its performance is assessed through comparisons with previous models, measurements, and simulations of magnetic field. The great advantages of the proposed approach in relation to the previous ones are its flexibility in the positioning and direction of antennas and the unlimited number of layers of soil. Moreover, this approach can be more accurate than classical ones in scenarios where the soil has a high conductivity below the antenna in an uplink scenario.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Fixed-Frequency Beam Steering Leaky-Wave Antenna With Integrated 2-Bit
           Phase Shifters

    • Free pre-print version: Loading...

      Authors: Xiaowei Cao;Changjiang Deng;Kamal Sarabandi;
      Pages: 11246 - 11251
      Abstract: In this communication, a reconfigurable 2-bit leaky-wave antenna (LWA) is proposed for low-cost fixed-frequency beam-steering applications. The proposed antenna consists of a microstrip transmission line loaded with several branches, a series of 2-bit phase shifters, and a $1times 8$ patch array. Each phase shifter is built by selecting the feed directions on the branch and introducing slot perturbation on the patch, thus no phase delay line is used. Only three p-i-n diodes are needed to control the 0°, 90°, 180°, and 270° states of the element. The reference phase $varphi _{0}$ , namely the phase of the first element, is utilized to enhance the peak gain of the array. The stopband effect of broadside beam is eliminated due to the perturbation on the patches. The prototype is tested at 3.6 GHz. The measured peak gain is 13.54 dBi, and the main beam can steer from $- mathrm{48}^{circ }$ to $+ mathrm{46}^{circ }$ .
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Corrections to “Optimization of Wireless Power Transfer Systems Enhanced
           by Passive Elements and Metasurfaces”

    • Free pre-print version: Loading...

      Authors: Hans-Dieter Lang;Costas D. Sarris;
      Pages: 11252 - 11252
      Abstract: In the above article [1], the authors have since become aware of two typos that require correction. They concern a missing operator and a missing factor in a derivation made in the appendix, notably equations (32) and (33) in the very last paragraph. Note that these typos do not in any way affect the results and conclusions in [1]. However, they may make it impossible for others to reproduce the presented results or use the proposed method for their own applications.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Frontiers in Computational Electromagnetics

    • Free pre-print version: Loading...

      Pages: 11253 - 11253
      Abstract: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • TechRxiv: Share Your Preprint Research with the World!

    • Free pre-print version: Loading...

      Pages: 11254 - 11254
      Abstract: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • IEEE Open Access

    • Free pre-print version: Loading...

      Pages: 11255 - 11255
      Abstract: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
  • Introducing IEEE Collabratec

    • Free pre-print version: Loading...

      Pages: 11256 - 11256
      Abstract: Advertisement.
      PubDate: Nov. 2022
      Issue No: Vol. 70, No. 11 (2022)
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 3.225.221.130
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-