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  Subjects -> ELECTRONICS (Total: 175 journals)
Showing 1 - 200 of 277 Journals sorted alphabetically
Acta Electronica Malaysia     Open Access  
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 7)
Advances in Electrical and Electronic Engineering     Open Access   (Followers: 5)
Advances in Electronics     Open Access   (Followers: 76)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Microelectronic Engineering     Open Access   (Followers: 13)
Advances in Power Electronics     Open Access   (Followers: 33)
Advancing Microelectronics     Hybrid Journal  
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 305)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 24)
Annals of Telecommunications     Hybrid Journal   (Followers: 9)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 9)
Archives of Electrical Engineering     Open Access   (Followers: 13)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Bioelectronics in Medicine     Hybrid Journal  
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 19)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 35)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access   (Followers: 1)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
China Communications     Full-text available via subscription   (Followers: 8)
Chinese Journal of Electronics     Hybrid Journal  
Circuits and Systems     Open Access   (Followers: 15)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 253)
Edu Elektrika Journal     Open Access   (Followers: 1)
Electrica     Open Access  
Electronic Design     Partially Free   (Followers: 104)
Electronic Markets     Hybrid Journal   (Followers: 7)
Electronic Materials Letters     Hybrid Journal   (Followers: 4)
Electronics     Open Access   (Followers: 85)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 10)
Electronics For You     Partially Free   (Followers: 91)
Electronics Letters     Hybrid Journal   (Followers: 26)
Elkha : Jurnal Teknik Elektro     Open Access  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 50)
Energy Harvesting and Systems     Hybrid Journal   (Followers: 4)
Energy Storage Materials     Full-text available via subscription   (Followers: 2)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 11)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 6)
Foundations and Trends® in Signal Processing     Full-text available via subscription   (Followers: 10)
Frequenz     Hybrid Journal   (Followers: 1)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 1)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 185)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 4)
IACR Transactions on Symmetric Cryptology     Open Access  
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 96)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 77)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 46)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 9)
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits     Hybrid Journal   (Followers: 1)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 65)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 69)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 55)
IEEE Transactions on Circuits and Systems for Video Technology     Hybrid Journal   (Followers: 19)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 39)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 19)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 26)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 70)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 11)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 12)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 5)
IET Cyber-Physical Systems : Theory & Applications     Open Access   (Followers: 1)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 35)
IET Nanodielectrics     Open Access  
IET Power Electronics     Hybrid Journal   (Followers: 45)
IET Smart Grid     Open Access  
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 18)
IETE Journal of Education     Open Access   (Followers: 4)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 13)
IJEIS (Indonesian Journal of Electronics and Instrumentation Systems)     Open Access   (Followers: 3)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 57)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 24)
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 12)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 18)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 10)
International Journal of Antennas and Propagation     Open Access   (Followers: 11)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 5)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 6)
International Journal of Control     Hybrid Journal   (Followers: 12)
International Journal of Electronics     Hybrid Journal   (Followers: 7)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 13)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 2)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 14)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 8)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 12)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 4)
International Journal of Power Electronics     Hybrid Journal   (Followers: 24)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 4)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 10)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 4)
International Journal of Wireless and Microwave Technologies     Open Access   (Followers: 6)
International Transaction of Electrical and Computer Engineers System     Open Access   (Followers: 2)
JAREE (Journal on Advanced Research in Electrical Engineering)     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 10)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 4)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription   (Followers: 1)
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 23)
Journal of Electrical Bioimpedance     Open Access   (Followers: 2)
Journal of Electrical Engineering & Electronic Technology     Hybrid Journal   (Followers: 7)
Journal of Electrical, Electronics and Informatics     Open Access  
Journal of Electromagnetic Analysis and Applications     Open Access   (Followers: 7)
Journal of Electromagnetic Waves and Applications     Hybrid Journal   (Followers: 8)
Journal of Electronic Design Technology     Full-text available via subscription   (Followers: 6)
Journal of Electronics (China)     Hybrid Journal   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Field Robotics     Hybrid Journal   (Followers: 2)
Journal of Guidance, Control, and Dynamics     Hybrid Journal   (Followers: 162)
Journal of Information and Telecommunication     Open Access   (Followers: 1)
Journal of Intelligent Procedures in Electrical Technology     Open Access   (Followers: 3)
Journal of Low Power Electronics     Full-text available via subscription   (Followers: 7)
Journal of Low Power Electronics and Applications     Open Access   (Followers: 9)
Journal of Microelectronics and Electronic Packaging     Hybrid Journal  
Journal of Microwave Power and Electromagnetic Energy     Hybrid Journal  
Journal of Microwaves, Optoelectronics and Electromagnetic Applications     Open Access   (Followers: 10)
Journal of Nuclear Cardiology     Hybrid Journal  
Journal of Optoelectronics Engineering     Open Access   (Followers: 4)
Journal of Physics B: Atomic, Molecular and Optical Physics     Hybrid Journal   (Followers: 28)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 11)
Journal of Semiconductors     Full-text available via subscription   (Followers: 5)
Journal of Sensors     Open Access   (Followers: 26)
Journal of Signal and Information Processing     Open Access   (Followers: 9)
Jurnal Rekayasa Elektrika     Open Access  
Jurnal Teknik Elektro     Open Access  
Kinetik : Game Technology, Information System, Computer Network, Computing, Electronics, and Control     Open Access  
Learning Technologies, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Magnetics Letters, IEEE     Hybrid Journal   (Followers: 7)
Majalah Ilmiah Teknologi Elektro : Journal of Electrical Technology     Open Access   (Followers: 2)
Metrology and Measurement Systems     Open Access   (Followers: 5)
Microelectronics and Solid State Electronics     Open Access   (Followers: 18)
Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 33)
Nanotechnology, Science and Applications     Open Access   (Followers: 6)
Nature Electronics     Hybrid Journal  
Networks: an International Journal     Hybrid Journal   (Followers: 6)
Open Journal of Antennas and Propagation     Open Access   (Followers: 8)
Optical Communications and Networking, IEEE/OSA Journal of     Full-text available via subscription   (Followers: 15)
Paladyn. Journal of Behavioral Robotics     Open Access   (Followers: 1)
Power Electronics and Drives     Open Access   (Followers: 1)
Problemy Peredachi Informatsii     Full-text available via subscription  
Progress in Quantum Electronics     Full-text available via subscription   (Followers: 7)
Pulse     Full-text available via subscription   (Followers: 5)
Radiophysics and Quantum Electronics     Hybrid Journal   (Followers: 2)
Recent Advances in Communications and Networking Technology     Hybrid Journal   (Followers: 3)
Recent Advances in Electrical & Electronic Engineering     Hybrid Journal   (Followers: 9)
Research & Reviews : Journal of Embedded System & Applications     Full-text available via subscription   (Followers: 5)
Security and Communication Networks     Hybrid Journal   (Followers: 2)
Selected Topics in Applied Earth Observations and Remote Sensing, IEEE Journal of     Hybrid Journal   (Followers: 53)
Semiconductors and Semimetals     Full-text available via subscription   (Followers: 1)
Sensing and Imaging : An International Journal     Hybrid Journal   (Followers: 2)
Services Computing, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Software Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 75)
Solid-State Circuits Magazine, IEEE     Hybrid Journal   (Followers: 13)
Solid-State Electronics     Hybrid Journal   (Followers: 9)
Superconductor Science and Technology     Hybrid Journal   (Followers: 2)
Synthesis Lectures on Power Electronics     Full-text available via subscription   (Followers: 3)
Technical Report Electronics and Computer Engineering     Open Access  
TELE     Open Access  
Telematique     Open Access  
TELKOMNIKA (Telecommunication, Computing, Electronics and Control)     Open Access   (Followers: 8)
Universal Journal of Electrical and Electronic Engineering     Open Access   (Followers: 6)
Visión Electrónica : algo más que un estado sólido     Open Access   (Followers: 1)
Wireless and Mobile Technologies     Open Access   (Followers: 6)
Wireless Power Transfer     Full-text available via subscription   (Followers: 4)
Women in Engineering Magazine, IEEE     Full-text available via subscription   (Followers: 11)
Електротехніка і Електромеханіка     Open Access  

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Journal Cover
IEEE Transactions on Antennas and Propagation
Journal Prestige (SJR): 1.309
Citation Impact (citeScore): 5
Number of Followers: 69  
  Full-text available via subscription Subscription journal
ISSN (Print) 0018-926X
Published by IEEE Homepage  [191 journals]
  • IEEE Transactions on Antennas and Propagation
    • 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: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • IEEE Transactions on Antennas and Propagation
    • 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: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Institutional Listings
    • Abstract: Presents the institutional listings associated with this issue of the publication.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Design of a Dual-Beam Dual-Polarized Offset Parabolic Reflector Antenna
    • Authors: Zhi-Ya Zhang;Yarui Zhao;Neng-Wu Liu;Lu-Yang Ji;Shaoli Zuo;Guang Fu;
      Pages: 712 - 718
      Abstract: In this paper, an offset reflector antenna with dual-beam and dual-polarization characteristics is developed to provide the angular diversity function for troposcatter communication system. The antenna system consists of a parabolic reflector and a dual-beam feed. For the dual-beam feed, two identical Ku-band feed elements are arranged side by side to generate two beams toward the reflector. The two beams are substantially nonoverlapping. The feed element is composed of a dielectric rod, a square waveguide, and an ortho-mode transducer. The dielectric rod is effective in reducing the beamwidth of the feed and providing more tapered illumination on the reflector in order to increase the antenna gain. Moreover, the developed antenna is able to produce two independent beams with the vertical and horizontal polarizations. The antenna was fabricated and tested with good agreement between the simulation and measurement results. The measured voltage standing wave ratios of the four feed ports are less than 1.5:1, and the beam separation angle is not more than 0.7° or about one time half-power beamwidth, and the antenna gain is higher than 45 dBi over the operating band from 14.5 to 15.35 GHz.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Multiport Power Combining Patch Antenna With Stable Reflection Coefficient
           and Radiation Pattern in Six Polarization States
    • Authors: Wen Duan;Xiu Yin Zhang;Shaowei Liao;Kai Xu Wang;Quan Xue;
      Pages: 719 - 729
      Abstract: A new kind of multiport power-combining patch antenna in multiple polarization states is proposed in this paper. The proposed antenna consists of a ground, a stacked patch, and a driven patch fed by four centrally symmetric ports. Based on the S-parameter analysis of the multiport antenna, six polarization states (0°, 90°, 45° linear polarization, and left-handed and right-handed circular polarization) with stable reflection coefficients and radiation pattern can be realized by controlling the input phases of four ports. In this way, it is not necessary to use extra feeding network to realize the multiple polarization states. Moreover, in addition to radiating electromagnetic energy just like conventional antennas, the proposed multiport antenna can also realize on-antenna power combining without the need of power combiner. As a result, the losses and size caused by extra power combiner and feeding network can be avoided. For verification, the four-port patch antennas in different polarization states are designed and compared. Moreover, a four-port antenna integrated with four power amplifiers is fabricated and measured. The results show that both on-antenna power-combining and multiple polarization states can be realized without the need of power combiner and polarization feeding network.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • All-Metal Endfire Antenna With High Gain and Stable Radiation Pattern for
           the Platform-Embedded Application
    • Authors: Yuefeng Hou;Yue Li;Zhijun Zhang;Magdy F. Iskander;
      Pages: 730 - 737
      Abstract: This paper presents a novel high-gain endfire slot antenna array fed by air-substrate microstrip line. It has a simple and compact structure consisting of a copper strip and two copper sheets. Designed based on the slot antenna array, the antenna could be embedded into a large metallic platform. The surface wave above the antenna radiates the energy to free space. Fed by the air-substrate microstrip line, the antenna works on the TEM mode. Therefore, the antenna obtains a suitable phase constant to realize stable endfire radiation pattern and could be designed by a long structure to realize high endfire gain. Because all of the antennas are designed by metal, it has the characteristics of high strength, easy fabrication, and low cost. With the radiating aperture of 3.5 wavelength, the antenna achieves a measured endfire gain of 11.81 dBi. The measured 1 and 3 dB gain bandwidths reach 4.5% and 8.4%, respectively. Good matching and stable endfire radiation pattern are obtained over the entire operating band from 3.75 to 4.15 GHz.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Asymmetric Half-Bowtie Antennas With Tilted Beam Patterns
    • Authors: William Dale Ake;Maria Pour;Adam Mehrabani;
      Pages: 738 - 744
      Abstract: A novel geometrical change is introduced to a broadband bowtie antenna to allow radiation beam tilting without the use of an engineered material. By halving the bowtie arms along their horizontal axis of symmetry and judicially removing parts of it, the phase line of the antenna can be controlled to achieve various magnitudes of tilted radiation patterns. Further bandwidth improvements are realized when the traditional triangular antenna is replaced with an elliptical equivalent. Using either geometry, the amount of tilt in free space across its bandwidth could vary from 0° to 60°. For the printed case, a unidirectional antenna pattern is tilted to approximately 40° along the useable bandwidth of 32% with a peak gain of about 5 dBi and a front-to-back ratio greater than 10 dB. A prototype antenna is fabricated and tested. The measured results satisfactorily validate the numerical ones.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • TCM-Based Bezel Antenna Design With Small Ground Clearance for Mobile
    • Authors: Changjiang Deng;Zhan Xu;Aidi Ren;Sean Victor Hum;
      Pages: 745 - 754
      Abstract: A high efficiency mobile terminal antenna with small ground clearance is presented in this paper. It consists of a chassis ground, an unbroken metal bezel, and two connecting metal strips. The theory of characteristic modes is applied to analyze the eigenmodes of the design in the frequency range of 600–3000 MHz. All the resonant modes are clearly tracked and identified. Each mode of the bezel has the even and odd states and can be illustrated by a two-slot model. The multiple modes of the bezel can be effectively excited by a simple probe. By changing the locations of the connecting strips and feeder and introducing an inductor, two fundamental modes and four higher order modes of the bezel are merged, providing sufficient bandwidth for mobile communication. The measured −6 dB bandwidths are 805–995 and 1340–2870 MHz, and the measured radiation efficiency is above 65% in both bands.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Isolation Enhancement for MIMO Patch Antennas Using Near-Field Resonators
           as Coupling-Mode Transducers
    • Authors: Min Li;Bing Guang Zhong;S. W. Cheung;
      Pages: 755 - 764
      Abstract: In this paper, a novel decoupling technique for closely packed patch antennas using near-field resonator (NFR) above each antenna element is proposed. The decoupling mechanism is illustrated by investigating the electric-field (E-field) and magnetic-field (H-field) distributions. The E-field distributions indicate that the NFRs above the patches serve as coupling-mode transducers to produce an orthogonal coupling mode at the desired resonance, leading to high port isolation between the patches. The H-field distributions demonstrate that the H-fields in the substrate are confined within the excited element, leading to the effective suppression of antenna mutual coupling. The NFR can be easily applied to multiple-input multiple-output (MIMO) antennas having multiple patch elements. Three practical decoupling examples are demonstrated and the simulation and measurement results show that impedance matching for each antenna port and isolation of better than 20 dB are achieved for all these examples using the NFRs. Moreover, for the H-plane and E-plane decoupling of wideband two-port MIMO antennas, wide decoupled impedance bandwidths of 6.1% and 5.8% are obtained, respectively. More results of radiation patterns reveal that good radiation performance is reserved with no reduction in realized gain or front-to-back ratio.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Compact Folded C-Shaped Antenna for Metal-Mountable UHF RFID Applications
    • Authors: Yong-Hong Lee;Eng-Hock Lim;Fwee-Leong Bong;Boon-Kuan Chung;
      Pages: 765 - 773
      Abstract: A new type of C-shaped antenna, which is designed by combining a loop antenna and a planar inverted-L antenna, is proposed for designing a miniature tag antenna for on-metal applications. The proposed tag antenna can be easily made by folding a piece of flexible substrate. It is electrically small and low in profile, with a circuit size of 40 mm $times40$ mm $times1.6$ mm ( $0.122lambda times 0.122lambda times 0.005lambda$ ). The antenna consists of five patch segments, which can be adjusted for achieving multiple degrees of tuning freedom. By tuning the antenna impedance, a conjugate match can be easily obtained. When mounted on a $20 times 20$ cm2 metal plate, the proposed tag antenna is able to achieve a maximum read distance of 9.2 m with equivalent isotropic radiated power of 4 W, which is much better than the conventional loop antenna. The operating frequency of the proposed tag antenna is found to be very stable and it is not affected much when the dimensions of the backing metal object are varied.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Miniaturized Novel-Shape Dual-Band Antenna for Implantable Applications
    • Authors: Farooq Faisal;Hyoungsuk Yoo;
      Pages: 774 - 783
      Abstract: In this paper, a miniaturized novel-shape dual-band implantable antenna operating in the industrial, scientific, and medical bands (902–928 MHz and 2.4–2.4835 GHz) is developed for battery-powered implants. The Rogers ULTRALAM ( $varepsilon _{r} =2.9$ and tan $delta =0.0025$ ) liquid crystalline polymer material with 0.1 mm thickness is used as both the substrate and superstrate. By employing the shorting strategy, a flower-shape radiating patch, and open-ended slots in the ground plane, the total volume of the proposed antenna is confined to $7 times 7.2times0.2$ mm3. In a homogeneous skin phantom, the presented antenna has a maximum gain of −28.44 and −25.65 dBi at 928 MHz and 2.45 GHz, respectively. The calculated maximum specific absorption rate values are in the safe limit and satisfy the IEEE C95.1-1999 and C95.1-2005 safety guidelines. The design, optimization, and analysis of the suggested antenna are performed using the finite difference time-domain- and finite-element method-based simulators. The results suggest that the flower-shape antenna exhibits fairly omnidirectional radiation patterns; therefore, it can be used for gastro applications and skin implantations. Through wireless communication link, we validated that at both frequencies (928 MHz and 2.45 GHz), 7 Kb/s and 78 Mb/s of data can be transmitted easily over more than 6 and 1.5 m, respectively. To verify the validity of the design and simulation results, measurements are performed by substituting the fabricated prototype in the American Society for Testing Materials and head phantoms containing saline solution. The proposed flower-shape antenna shows salient performance parameters -ompared with the recently proposed antennas.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Novel Steerable Dual-Beam Metasurface Antenna Based on Controllable
           Feeding Mechanism
    • Authors: Wanchen Yang;Lizheng Gu;Wenquan Che;Qian Meng;Quan Xue;Cao Wan;
      Pages: 784 - 793
      Abstract: A novel steerable dual-beam metasurface antenna (MSA) with controllable feeding mechanism is proposed. The proposed MSA consists of $7 times 10$ square metasurface cells and is fed by a completely symmetrical controllable network, which includes three dumbbell-shaped coupling slots etched on the ground and two-port stepped impedance line beneath the ground. The network can flexibly control the magnitude and phase of the coupling energy from the feeding line to the radiated metasurface cells via the slots, so as to realize two desired symmetrical beams. Owing to good directional radiation of the MSA, the beams of the proposed MSA exhibit better front-to-back ratio, higher gain, and higher channel isolation than those of traditional traveling-wave slot antennas. Moreover, benefiting from the controllable feeding mechanism, impedance matching, sidelobe suppression, and isolation of the ports can be further improved. Consequently, the two achieved beams are, respectively, oriented at ±30°in azimuth plane with 10 dB beamwidth of about 120°, high-peak gains of 12.8 dBi and cross level at two beams junction of about −10 dB; meanwhile, the isolation of the two ports is over 15 dB within the band of interests (5.23 and 5.40 GHz). For demonstration of the design strategy, one $1 times 2$ dual-beam MSA array with gain of 14.8 dBi and similar beam performance is designed and fabricated. Due to the controllable steerable beams and the simple mechanism without complex beamforming networks, phase shifters or large footprint, the proposed steering dual-beam MSA array can be expected to find potential applications in multibeam base stations.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Compact Metasurface-Enabled Dual-Band Dual-Circularly Polarized Antenna
           Loaded With Complementary Split Ring Resonators
    • Authors: Taiwei Yue;Zhi Hao Jiang;Douglas H. Werner;
      Pages: 794 - 803
      Abstract: In this paper, the design and experimental validation of a novel miniaturized dual-band dual-circularly polarized (CP) metasurface (MS) antenna is reported. The proposed antenna is enabled by an engineered MS-based artificial ground that supports simultaneous dual-band functionality and dual-CP unidirectional radiation. The artificial ground is a highly truncated dual-layer MS containing an array of $2 times 2$ unit cells. Each unit cell is comprised by a patch and a complementary split ring resonator (CSRR) printed on the top and bottom surfaces of the substrate, respectively. A printed feeding monopole antenna is integrated with the MS to form a low-profile dual-band dual-CP antenna with a thickness of $0.04{lambda }_{0}$ , where ${lambda }_{0}$ is the free-space wavelength at the first operational band. A dispersion analysis of the unit cell is carried out both analytically and numerically to illustrate the working principle of the proposed antenna. This reveals that the bianisotropic response and the orientation of the CSRRs jointly provide distinct dispersion behavior along two orthogonal directions of the dual-layer MS, enabling the desired dual-band dual-CP radiation. Moreover, the CSRRs also facilitate antenna miniaturization, yielding an overall footprint of only $0.33 lambda _{0}times 0.33lambda _{0}$ . In order to verify the antenna design, a prototype is fabricated and tested, and strong agreement between simulated and measured results is observed, experimentally achieving a 50 MHz bandwidth, and a peak gain of 3.95 and 5.29 dBi at the two targeted bands with opposite handedness for the radiated waves.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • The Novel W Parasitic Strip for the Circularly Polarized Microstrip
           Antennas Design and the Mutual Coupling Reduction Between Them
    • Authors: Kun Wei;Bo-Cheng Zhu;
      Pages: 804 - 813
      Abstract: This paper presents a novel W-shaped parasitic strip to design the circularly polarized (CP) simultaneous transmit and receive antennas and reduce the mutual coupling (MC) between them. By disturbing the current fields and inducing the current distribution on the antenna patches, the CP radiation and MC reduction are achieved. The designed CP antennas have 30 MHz 10 dB impedance bandwidth, 16 MHz 3 dB axial ratio bandwidth, and approximate 5.08 dBic peak CP gain. This technique also reduces the MC from −7 to −50 dB when the antennas are placed with a $0.18lambda _{0}$ center-to-center distance and a $0.033lambda _{0}$ edge-to-edge distance, where $lambda _{0}$ is the free-space wavelength. When achieving the MC reduction, the antenna radiation pattern restores to that of the isolated antenna. Furthermore, the antenna CP gain and efficiency are improved comparing those of the antenna without the parasitic strip or the classic corner cut CP antenna.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • An Efficient Broadband Slotted Rectenna for Wireless Power Transfer at LTE
    • Authors: Yanyan Shi;Yue Fan;Yan Li;Lan Yang;Meng Wang;
      Pages: 814 - 822
      Abstract: A compact and broadband rectifying antenna (rectenna) which consists of a novel slotted antenna and an efficient rectifying circuit is presented for wireless power transfer at LTE-2300/2500 band. Three different broadband antennas have been investigated and compared. It is found that the newly designed antenna which combines the annular slot radiation patch and a slotted ground plane (GP) has the widest bandwidth and the best matching characteristic. A new broadband dual-stub matching network is proposed to maximize the transmission of wireless power and enhance the reliability of the rectifier when the input power and load varies. In addition, the ground of the rectifier is directly connected to the GP of the antenna for compactness and low energy loss. The proposed designs have been simulated, fabricated, and tested. The results indicate that the proposed receiving antenna performs well at LTE band with a wide bandwidth from 2 to 3.1 GHz. The maximum efficiency of the proposed rectenna reaches 70% at 2.5 GHz under the input power of 5 dBm. Furthermore, the rectenna remains at a relatively efficient power conversion when the load varies in a wide range from 2 to 20 $text{k}Omega $ under different low input power, which is of great significance when the ambient radio frequency(F) signal is weak. Therefore, the rectenna is potentially applicable to a wide range of low-power electronic devices by harvesting RF energy at LTE band.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Broadside Scanning Asymmetric SIW LWA With Consistent Gain and Reduced
    • Authors: Ravi Shaw;Mrinal Kanti Mandal;
      Pages: 823 - 833
      Abstract: In this paper, a backward-to-forward continuous beam scanning leaky wave antenna is presented in substrate integrated waveguide technology. The antenna radiates from a continuous longitudinal slot etched on its broad wall. The slot is excited by using periodic H-plane steps. An impedance matched unit cell structure is used to suppress the open stopband in the broadside direction. Bloch wave analysis is used to obtain the propagation characteristics of the antenna. However, due to radiation being obtained only from the shunt-type radiating element, namely, the longitudinal slot, a gain dip is observed in the broadside direction. Transversal asymmetry is then introduced in the structure to eliminate the gain dip and obtain the consistent gain. A prototype of the antenna is fabricated and measured. Continuous beam scanning is achieved from −29º to +30º about the broadside direction with a gain variation of less than 2 dB over 8.0–12.4 GHz. A measured peak gain of 16.1 dBi is obtained. Key structural design parameters of the antenna are identified for controlling the leakage rate. Next, Taylor tapered aperture illumination is used to obtain low sidelobe level (SLL). The Taylor tapered antenna is also fabricated with the measured SLL below −21 dB.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Optimizing High-Power Ultra-Wideband Combined Antennas for Maximum
           Radiation Within Finite Aperture Area
    • Authors: Shao-fei Wang;Yan-zhao Xie;Ming-Xiang Gao;Yang-Xin Qiu;Yury A. Andreev;
      Pages: 834 - 842
      Abstract: In this paper, the combined antenna array is developed to maximize the effective potential gain ( $G_{ep}$ ) within finite aperture area for the high-power ultra-wideband (UWB) radiation. The idea is to make the antenna element as small as possible, so that more elements can be arranged within the prescribed aperture area to maximize $G_{ep}$ of the UWB system. On the other hand, the antenna element should match the pulse excitation. This means that in the frequency domain, the working band of the antenna element should cover the spectrum of the radiated pulse, and in the time domain, critical parameters of the radiated field (e.g., rise time of the monopolar pulse) should not be distorted, and those can be the principles for the UWB antenna to match the pulsed excitation, based on which the minimum size of the antenna element can be determined. With this method, a four-element combined antenna array is designed. Also, an impedance transformer and power divider are designed to feed the antenna array. Also, a big combined antenna is developed with the same aperture dimensions (30 cm $times30$ cm) as the antenna array. Then, the performances of the antenna array and the big antenna are measured and compared. Compared with the big antenna, $G_{ep}$ of the antenna array is 21% higher under the applied excitation, which indicates that the proposed method can significantly improve $G_{ep}$ of the UWB system within the prescribed aperture area. Finally, the antenna array is furthermore optimized by adjusting the distances between the elements, and $G_{e-}$ is improved by another 11%, the total improvement is 33%, and the corresponding effective potential gain is 1.49.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Wideband Monostatic Co-Polarized Co-Channel Simultaneous Transmit and
           Receive Broadside Circular Array Antenna
    • Authors: Ehab A. Etellisi;Mohamed A. Elmansouri;Dejan S. Filipovic;
      Pages: 843 - 852
      Abstract: A novel wideband monostatic circularly co-polarized co-channel simultaneous transmit and receive (C-STAR) broadside circular array antenna with a partially shared beam-forming network (BFN) is proposed. The configuration consists of four sequentially rotated two-arm Archimedean spiral antennas, backed by a finite ground plane and driven by a BFN. Every two diagonal antenna pairs are fed with differential phases to obtain similar co-polarized broadside transmitting (TX) and receiving (RX) beams. Each individual element has single feeding port and operates simultaneously as TX and RX over the same frequency. The proposed C-STAR approach utilizes antenna orientation, geometric symmetry, and partially shared BFN to overcome self-interference. In the absence of asymmetry and BFN imbalances, complete wideband self-interference cancellation is achieved without relying on time-, frequency-, space-, pattern-, antenna/port-, or polarization-multiplexing. The fabricated prototype has measured TX/RX isolation >38 dB, axial ratio 0.93.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Dual-Band Shared-Aperture Antenna With Large Frequency Ratio, High
           Aperture Reuse Efficiency, and High Channel Isolation
    • Authors: Jin Fan Zhang;Yu Jian Cheng;Yan Ran Ding;Chun Xu Bai;
      Pages: 853 - 860
      Abstract: The operating frequency of future communication systems will cover unlicensed millimeter-wave bands as well as existing microwave bands. Large frequency ratio antennas that can be applied to both frequency bands simultaneously and maintain the high isolation between the two channels are difficult to design. This paper presents a new design of dual-band shared-aperture antenna based on the concept of structure reuse. The antenna consists of a patch antenna working at 3.5 GHz and a $12 times 12$ substrate integrated waveguide (SIW) slot array antenna working at 60 GHz. The frequency ratio of this shared-aperture antenna is 17. In this design, the overall structure of the SIW slot array antenna is employed as the radiator of the patch antenna. With this new scheme, the high aperture reuse efficiency can be achieved. Meanwhile, the millimeter-wave antenna based on the SIW technology has the high-pass nature to reject the lower frequency signal. A compact microstrip resonant cell that acts as a low-pass filter is connected in series on the feedline of the microwave antenna to suppress the upper frequency signal. Thus, the channel isolation between the patch and the SIW slot array antennas can be more than 130 dB at 3.5 GHz and 65 dB at 60 GHz.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Differentially Fed Dual-Polarized Magnetic Dipole Antenna for Spaceborne
    • Authors: Xue Ren;Shaowei Liao;Quan Xue;
      Pages: 861 - 871
      Abstract: This paper presents a novel differentially fed dual-polarized magnetic dipole antenna with stable radiation pattern, platform independence, wide bandwidth, and robust structure for spaceborne applications. The proposed antenna is formed by a dual-polarized magnetic dipole backed by a specially designed rectangular cavity. The magnetic dipole consists of two perpendicular parallel-plate waveguides with stepped edges to broaden the impedance bandwidth, providing good structural reliability which is critical to spaceborne antennas. A cross-shaped conductor fed by two pairs of capacity coupling feeding probes is utilized to drive the dual-polarized magnetic dipole antenna. The specially designed rectangular cavity has four metal plates in four corners to shape the radiation pattern at E- and H-planes. Furthermore, thanks to the cavity, the size of the conducting platform that the antenna mounted on has limited impact on antenna’s electrical performances, particularly the radiation pattern. A prototype is fabricated and tested. Measured results show that the antenna achieves a fractional bandwidth of 18.5% with −10 dB reflection coefficient. The realized gain is about 8.5 dBi. A stable radiation pattern with a 3 dB beamwidth of 70° ± 3° and −4 dBi maximum beamwidth of 152° is observed. The measured cross-polarization is lower than −20 dB within °65°. Measured results are in good agreement with simulation ones.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Wideband, Single-Layer Reflectarray Exploiting a Polarization Rotating
           Unit Cell
    • Authors: Hung Luyen;Zhe Yang;Meng Gao;John H. Booske;Nader Behdad;
      Pages: 872 - 883
      Abstract: We present a new technique for designing wideband, single-layer reflectarray antennas. The proposed reflectarray exploits a wideband, polarization rotating unit cell that rotates the polarization of the reflected wave with respect to that of the incident wave by 90°. This unit cell and its mirror image were used as 1 bit spatial phase shifters capable of providing a 0°/180° phase shift over a wide bandwidth of 5.4–12.7 GHz. Using this, a reflectarray antenna with 1 bit phase quantization was designed to operate at ${X}$ -band with aperture dimensions of $28.8,,text {cm}times 28.8$ cm and a focal length of 30 cm. A prototype of the proposed reflectarray was fabricated and characterized using a spherical near-field measurement system. We determined the antenna’s 3 dB gain bandwidth to be approximately 37.4% with a maximum realized gain of 24.2 dBi. Over its entire band of operation, the polarization purity of the antenna remains better than 13 dB and sidelobe levels of better than 12 dB were achieved.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • An Intuitive Way to Understand Mutual Coupling Effects in Antenna Arrays
           Using the Poynting Streamline Method
    • Authors: Junming Diao;Lu Liu;Karl F. Warnick;
      Pages: 884 - 891
      Abstract: The flow of energy around array antenna in receiving mode can be modeled by generating streamlines of the Poynting vector field. From the streamlines that terminate on the array element loads, a geometrical shape can be assigned to the effective area of the array. These concepts provide an intuitive tool for understanding mutual coupling effects in antenna arrays. The decrease in directivity associated with mutual coupling effects, the so-called element-gain paradox, can be explained by the overlap of the element effective area shapes. The critical element spacing for the element-gain paradox effect can be predicted from the effective area shape for a single isolated array element. Antenna design for minimizing mutual coupling, which is of interest in multiple input multiple output communications systems, magnetic resonance imaging arrays, astronomical arrays, and other applications, can be guided by analysing the effective area shape for a single isolated array element.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • 24 GHz Horizontally Polarized Automotive Antenna Arrays With Wide Fan Beam
           and High Gain
    • Authors: Chia-An Yu;Eric S. Li;Huayan Jin;Yue Cao;Guan-Ren Su;Wenquan Che;Kuo-Sheng Chin;
      Pages: 892 - 904
      Abstract: In this paper, two 24 GHz horizontally polarized $1 times 8$ patch antenna arrays were developed for automotive radar applications. The proposed antenna arrays offer the advantages of wide fan beams and high gain. The far-field radiation patterns are widened in the E-plane by disturbing the near-field distribution of each driven patch. In Design I, the driven patch is loaded with a parasitic loop, which functions as a director in the E-plane. Due to the directing effect, the E-plane beamwidth can be increased. The experimental verification prepared for Design I showed that a beamwidth of 130° and a gain of 12.2 dBi can be achieved through this method. To further enhance the beamwidth, another array with each patch loaded with parasitic mushroom-like elements was proposed by Design II. The PMLEs are 180° out of phase to their corresponding driven patch. The cancelation effects can be properly managed to slightly sacrifice the gain of the array in return for a wider beamwidth in the E-plane. Design II exhibits a wider beamwidth of 150° and a lower gain of 11.1 dBi.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Wide Scanning Characteristics of Sparse Phased Array Antennas Using an
           Analytical Expression for Directivity
    • Authors: Ashutosh Kedar;L. P. Ligthart;
      Pages: 905 - 914
      Abstract: This paper presents a generalized analytical expression for directivity of phased array antennas (PAAs). It includes important design consideration of PAAs such as arbitrary element type and array geometry, complex excitations, mutual coupling, scan angle, and embedded element pattern. We also present an approximate expression of directivity, helpful for quick analysis of large PAAs overcoming computing time constraints of analytical expressions. It provides a quick PAA design tool for predicting accurate locations of blind spots in desired scan volume due to the chosen array geometry. This paper also presents the study on wide scan characteristics of periodic sparse PAAs using the proposed expressions.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • $W$+ -Band+LTCC+Transition+From+Microstrip+Line+to+Ridge+Gap+Waveguide+and+its+Application+in+77/79+GHz+Antenna+Array&rft.title=IEEE+Transactions+on+Antennas+and+Propagation&rft.issn=0018-926X&;&rft.aufirst=Yongrong&;Wenjie+Feng;Hao+Wang;Wenquan+Che;Quan+Xue;Jicai+Wang;Junzhi+Zhang;Xingcheng+Qian;Ming+Zhou;Baolin+Cao;">Novel $W$ -Band LTCC Transition From Microstrip Line to Ridge Gap
           Waveguide and its Application in 77/79 GHz Antenna Array
    • Authors: Yongrong Shi;Wenjie Feng;Hao Wang;Wenquan Che;Quan Xue;Jicai Wang;Junzhi Zhang;Xingcheng Qian;Ming Zhou;Baolin Cao;
      Pages: 915 - 924
      Abstract: An ultra-wideband transition from microstrip line to ridge gap waveguide (GWG) is proposed for W-band system integration with antenna array and a transceiver. Substrate integrated waveguide bridge is used in the proposed transition for electromagnet wave propagation between microstrip line and ridge GWG, which can realize impedance matching for a wideband frequency range. Back-to-back transition prototypes are fabricated by the low-temperature co-fired ceramic (LTCC) technique, and the probe measurement results show that the transition can work at W-band. Moreover, the application of the proposed transition in a LTCC slot antenna array with magnetic coupling ridge GWG feeding network operated at 77/79 GHz is studied comprehensively. The antenna performance measurements demonstrate that the proposed transition has a potential massive application in the GWG active antennas.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Multibeam Digital Array Receiver Using a 16-Point Multiplierless DFT
    • Authors: Viduneth Ariyarathna;Diego F. G. Coelho;Sravan Pulipati;Renato J. Cintra;Fábio M. Bayer;V. S. Dimitrov;Arjuna Madanayake;
      Pages: 925 - 933
      Abstract: An $N$ -element array with receivers subject to an $N$ -point spatial fast Fourier transform (FFT) leads to $N$ directionally orthogonal radio frequency (RF) beams. FFTs are fast algorithms for computing the $N$ -point discrete Fourier transform (DFT) at reduced complexity. The brute-force computation of a DFT requires $mathcal {O}(N^{2})$ multiplications while an FFT provides the same computation at $mathcal {O}(N log N)$ multiplications. The digital chip area and power consumption of the DFT computation are still dominated by the multipliers required by the FFT used. In this paper, an approximation to the 16-point DFT is proposed which maintains mathematical properties close to the ideal 16-point DFT to obtain 16 RF beams by computing an approximate spatial DFT in every clock cycle at significantly lower area and power in the digital realization. The proposed approximation can be implemented using FFT-like fast algorithms that are multiplierless, thereby further reducing the digital chip area and power consumption associated with multiplication in a conventional FFT approach to zero. A 16-beam beamformer employing a 16-element linear array of patch antennas, direct-conversion receivers, and a Xilinx Virtex-6 field-programmable gate array-based real-time digital back-end clocked at 240 MHz are described as an example realization of 16 complex-valued (IQ) receive-mode RF beams, centered at 2.4 GHz with 120 MHz of bandwidth per beam.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Design of Sum and Difference Patterns With Common Nulls and Low SLLs
           Simultaneously in the Presence of Array Errors
    • Authors: Yanhong Xu;Xiaowei Shi;Anyi Wang;Jingwei Xu;
      Pages: 934 - 944
      Abstract: Sum ( $Sigma$ ) and difference ( $Delta$ ) beampatterns are commonly utilized to estimate the bearings of targets in the radar system. However, the nulls of $Delta $ -pattern are not always aligned with those of $Sigma $ -pattern, and this phenomenon would become more severe in practical scenario since the array errors exist. Meanwhile, the sidelobe level (SLL) of the array would also increase due to the unavoidable errors. The above-described factors would dramatically decrease the performance of radar in the adaptive suppression of interference. To increase the output signal-to-interference-plus-noise ratio of a radar system, this paper presents an approach to design the low SLL $Sigma Delta $ -patterns where the nulls of the $Delta $ -pattern, excluding the central null, are always aligned with those of the $Sigma $ -pattern in the presence of errors. Two schemes are addressed to obtain the covariance matrix for null-alignment constraint, which is exploited to force nulling in desired angles accordingly. In the sequel, the matrix tapering method is adopted to broaden the nulls and enhance the robustness for the possible errors. With the proposed approach, the low SLL and nulls alignment can be achieved simultaneously. Numerical examples are provided and discussed to demonstrate the effectiveness of the proposed solution, including the results based on a linearly spaced microstrip array antenna.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Wideband Planar Aperture Array Using Interconnected Crossed Rings
    • Authors: Yongwei Zhang;Anthony K. Brown;
      Pages: 945 - 950
      Abstract: A 5:1 frequency bandwidth aperture array antenna based on a new planar structure is reported. Dual polarization is implemented with high cross-polarization discrimination over ±45° scan angle from zenith. It is a low-loss cost-effective approach using minimum dielectric materials. In the proposed planar antenna array design, a mutual coupled interconnected ring structure is used which extends the operational frequency band to the region where the element separation can be considerably greater than half a wavelength, unlike the previously reported interconnected array structures. Hence, the total number of elements can be reduced for a specified aperture size. The dual polarization has coincident phase centers and in the implementation reported here two low-noise amplifiers on the same board are integrated with a pair of dual-polarized elements to form an active array. A 10 by 10 element array prototype of the design has been manufactured and the measured results confirm it as a low cost, high-performance front-end solution.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Optimal Phase-Matching Strategy for Beam Scanning of Sub-Arrayed Phased
    • Authors: Paolo Rocca;Mohammad Abdul Hannan;Lorenzo Poli;Nicola Anselmi;Andrea Massa;
      Pages: 951 - 959
      Abstract: The design of phased array antennas generating two functional beams is addressed here. The first/primary beam is fixed and it is generated at the element level (EL) through the complex (amplitude and phase) weighting coefficients, while the second/secondary one is synthesized at the subarray level by aggregating the array elements into nonoverlapped clusters and using additional phase shifters at the clusters outputs. Toward this end, the subarray configuration is determined by means of an ad hoc iterative method aimed at reducing the unavoidable quantization lobes, while the synthesis of the subarray phase coefficients; once the excitations at the EL have been set, is cast as a phase-matching problem whose analytic solution is optimal since it guarantees the minimum least-square error with respect to a reference phase distribution. A set of representative numerical results is reported and discussed to validate the proposed design approach and to point out its features and potentialities when addressing the synthesis of both pencil and shaped-beam power patterns.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Low-Profile Circular Patch Array Fed by Slotted Substrate Integrated
    • Authors: Jun Xu;Wei Hong;Zhi Hao Jiang;Hui Zhang;
      Pages: 960 - 970
      Abstract: A linear array antenna comprising circular-shaped patches fed by slotted substrate integrated waveguide is proposed. The slotted circular-shaped patch operates at the quasi-TM21 mode, which produces boresight radiation with an improved gain due to the introduction of additional slot loadings in the middle space of the circular-shaped patch. Comparisons among the proposed $1 times 8$ linear array antenna and two other traditional linear arrays used in automotive radars are presented, highlighting the superior performance of the proposed linear array, i.e., higher gain and wider 1 dB gain bandwidth. Several key geometrical design parameters, which are critical to the performance of the array antenna, are studied and analyzed to provide a better understanding of the proposed array antenna. A $4times 8$ planar array antenna incorporating four $1times 8$ linear arrays is further designed to verify the extension capability of the proposed linear array. Both the linear array and the planar array antennas were fabricated and measured, showing a good agreement between simulation and measured results, thus validating the designs. The proposed array antenna can be a good candidate for millimeter-wave automotive radar applications.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Patch Antenna Array Designs for Wireless Communication Applications Inside
           Jet Engines
    • Authors: Aparna Krishna;Aya. F. Abdelaziz;Tamer Khattab;
      Pages: 971 - 979
      Abstract: In this paper, two different patch antenna geometries are proposed for wireless sensor applications involving electromagnetic propagation from inside the jet engine to our designed relaying antenna at the rim of the inlet. First, an enhanced modified version of our earlier proposed two-element circular patch antenna array is proposed. We follow with a fresh new design based on two-element array of hybrid rectangular circular patch antenna geometry. Both antenna designs are discussed in light of basic governing equations enabling initial design calculations, intuitions behind selecting the design elements based on desired propagation characteristics, simulation results, as well as fabrication and experimental measurements. Because of the environmental constraints, the proposed antennas need to be an extremely low profile and ultrathin. The proposed relaying antennas are designed to have a dual-beam pattern, one of which is directed toward the inside of the jet engine. The antennas are simulated using HFSS as well as fabricated and measured inside an anechoic chamber. Experimental results, which sufficiently agree well with the simulation results, demonstrate the achievement of the desired characteristics by fabricated antennas for deployment on jet engines.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • An Optimization Method for the Synthesis of Flat-Top Radiation Patterns in
           the Near- and Far-Field Regions
    • Authors: Xiao Cai;Wen Geyi;
      Pages: 980 - 987
      Abstract: This paper presents an optimization method for the design of array antennas with flat-top radiation patterns in the far-field and near-field regions, in which the synthesis of flat-top radiation patterns is formulated as a quadratically constrained quadratic programing (QCQP) problem with equality constraints. It is shown that the notoriously difficult QCQP problem can be linearized and simplified for the synthesis of flat-top radiation patterns in the far-field region and can be extended to the near-field region by introducing a weighted diagonal matrix. To validate the optimization theory, a flat-top sector beam antenna for base station applications and an RFID bookshelf reader antenna are designed and fabricated. Simulation and measurement results show that the base station antenna operating at 5.4 GHz provides a flat-top radiation pattern with less than 1 dB fluctuation in the desired covering range of the main beam. The five-element RFID reader antenna working in the UHF band for library applications is demonstrated to generate uniform electric field intensity with less than 3 dB fluctuation across the whole bookshelf.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Millimeter-Wave Low-Profile Continuous Transverse Stub Arrays With Novel
           Linear Source Generators
    • Authors: Yunlong Lu;Qingchun You;Yi Wang;Yang You;Jifu Huang;Ke Wu;
      Pages: 988 - 997
      Abstract: This paper presents a new type of continuous transverse stub (CTS) antenna array with a novel linear source generator (LSG). The conventional multilayer parallel-plate waveguide (PPW) feed and pillbox structure are eliminated and replaced with a more compact partially corporate feed network. This helps to achieve a lower profile (or reduction of antenna layers) and high performance of broadband and high efficiency. For validation, two prototypes are demonstrated—one based on hollow waveguides operating at 34–41 GHz (Array-I) and the other based on substrate integrated waveguides operating at 24.5–29.5 GHz (Array-II). Both arrays contain eight radiation slots, fed from a single-layer PPW junction. The required quasi-transverse electromagnetic wave excitations are achieved by using the novel LSG of a jagged cavity structure. The detailed design methodology and analyses are provided in this paper. Measurements show that antenna efficiencies of over 83% and 82% with the peak gains of better than 27.6 and 20.6 dBi are achieved for Array-I and Array-II, respectively. These low-profile CTS designs are well suited for current and emerging millimeter-wave applications such as 5G and point-to-point communications.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Designing Anisotropic, Inhomogeneous Metamaterial Devices Through
    • Authors: Brian B. Tierney;Anthony Grbic;
      Pages: 998 - 1009
      Abstract: A method for designing multi-input, multi-output metamaterial devices is presented. The devices are 2-D anisotropic, inhomogeneous media. The design technique consists of a custom finite-element method solver coupled to a constrained, nonlinear minimization algorithm. The design method has advantages over existing metamaterial design methods such as transformation optics, in that material constraints can be imposed and multi-input, multi-output functionality allowed. Transformation optics devices only achieve multi-input, multi-output functionality through geometrical symmetry. The gradient-based optimization method employed in the metamaterial design process is fast given that an analytic expression for the gradient of the cost function can be written. The proposed technique is demonstrated through the design of two beamforming devices. A commercial full-wave solver is used to validate the design approach. The constitutive parameters of these 2-D designs can be implemented using printed-circuit board metamaterials, such as tensor transmission-line metamaterials.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Beam Frame Representation for Ultrawideband Radiation From Volume Source
           Distributions: Frequency-Domain and Time-Domain Formulations
    • Authors: Ram Tuvi;Ehud Heyman;Timor Melamed;
      Pages: 1010 - 1024
      Abstract: We present two novel beam-summation schemes for radiation from time-harmonic or time-dependent volume source distributions, where the field is expanded using a discrete phase-space set of beam-wave propagators. The generic term “beams” is used here for both the frequency-domain and the time-domain formulations where the propagators are isodiffracting Gaussian beam or isodiffracting pulsed beams, respectively. The formulations are structured upon the recently formulated “beam-frame” theorem that establishes these phase-space beam sets as frame sets everywhere in the propagation domain and not only over the aperture plane as in previous formulations. The expansion coefficients are obtained by projecting the source distributions over the dual beam-frame sets that have essentially the same structure as the basic sets. As such, these formulations constitute local generalization to the conventional plane waves or Green’s function formulations, and also reduce the overall degrees of freedom needed to describe the radiated field. As demonstrated by the numerical examples, they resolve the local features of the source distributions in space time, and hence provide a basis for a new local inverse scattering theory to be presented subsequently.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Exceptional Points of Degeneracy and Branch Points for Coupled
           Transmission Lines—Linear-Algebra and Bifurcation Theory Perspectives
    • Authors: George W. Hanson;Alexander B. Yakovlev;Mohamed A. K. Othman;Filippo Capolino;
      Pages: 1025 - 1034
      Abstract: We provide a new angle to investigate exceptional points of degeneracy (EPD) relating the current linear-algebra point of view to bifurcation theory. We apply these concepts to EPDs related to propagation in waveguides supporting two modes (in each direction), described as a coupled transmission line. We show that EPDs are singular points of the dispersion function associated with the fold bifurcation connecting multiple branches of dispersion spectra. This provides an important connection between various modal interaction phenomena known in guided-wave structures with recent interesting effects observed in quantum mechanics, photonics, and metamaterials systems described in terms of the algebraic EPD formalism. Since bifurcation theory involves only eigenvalues, we also establish the connection to the linear-algebra point of view by casting the system eigenvectors in terms of eigenvalues, analytically showing that the coalescence of two eigenvalues results automatically in the coalescence of the two respective eigenvectors. Therefore, for the studied two-coupled transmission-line problem, the eigenvalue degeneracy explicitly implies an EPD. Furthermore, we discuss in some detail the fact that EPDs define branch points in the complex frequency plane, we provide simple formulas for these points, and we show that parity-time (PT) symmetry leads to real-valued EPDs occurring on the real-frequency axis.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Exact Solution for the Protected TEM Edge Mode in a PTD-Symmetric
           Parallel-Plate Waveguide
    • Authors: Enrica Martini;Mário G. Silveirinha;Stefano Maci;
      Pages: 1035 - 1044
      Abstract: A parity time-reversal duality symmetric structure constituted by a perfect electric conductor and perfect magnetic conductor (PMC) parallel plate waveguide is analyzed. This waveguide supports unimodal transverse electromagnetic (TEM) edge mode propagation protected against backscattering from a certain class of deformations and defects. The TEM solution is found in analytical form by using three different methods, namely, conformal mapping, mode-matching, and Fourier-transform methods. It is shown through numerical simulations that the mode propagation is robust with respect to deformations such as 90° bends and discontinuities such as transition to free space. Implementation of the PMC boundary conditions via both a bed of nails and a mushroom structure is also successfully investigated.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Miniaturized Frequency-Selective Rasorber With a Wide Transmission Band
           Using Circular Spiral Resonator
    • Authors: Qiang Chen;Di Sang;Min Guo;Yunqi Fu;
      Pages: 1045 - 1052
      Abstract: This paper presents a miniaturized frequency-selective rasorber (FSR) that has a wide transmission band with low insertion loss and a wide absorption band below the transmission band. The FSR is composed of a resistive sheet and a bandpass frequency-selective surface (FSS). The unit cell of the resistive sheet is a resistor-loaded hexagonal metallic loop, each side of which is inserted with a circular spiral resonator (CSR) in the center. The CSR is equivalent to a parallel LC circuit that has a high inductance and low parasitic capacitance. At a high frequency of 10 GHz, the CSR resonates to be infinite impedance, around which a 0.5 dB transmission band of 8.68–11.34 GHz is produced. The bandpass FSS is a triple-layer FSS in which two layers of identical hexagonal patches are coupled through a layer of hexagonal aperture; it has a fast rolloff 0.5 dB transmission band of 8.2–11.33 GHz, which almost coincides with that of the resistive sheet. The 1 dB transmission band of the FSR by placing the resistive sheet on the bandpass FSS is 8.3–11.07 GHz. At low frequency, the FSR performs as an absorber, and the 10 dB absorption band is 2.4–7.1 GHz. In addition, due to its tiny physical sizes of only $1.2,,text {mm}times 1.6$ mm, the CSR can be viewed as a lumped element circuit with a high inductance, in which the parallel resonance is almost independent to the incident angle. The transmission performance of the FSR has a good independence of polarizations and incident angles. A prototype of the proposed FSR is fabricated and measured to validate the design.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Bandstop Frequency-Selective Structures Based on Stepped-Impedance Loop
           Resonators: Design, Analysis, and Measurement
    • Authors: Wensong Wang;Qunsheng Cao;Yuanjin Zheng;
      Pages: 1053 - 1064
      Abstract: A new dual-polarized and dual-band second-order bandstop 3-D frequency-selective structure (FSS) is proposed with arbitrary band ratio. Compared with the square loop, the stepped-impedance (SI) loop resonator performs at lower basic resonant frequency and increases the first spurious resonant frequency. Different half-wavelength SI loop resonators are analyzed, compared, and employed to design single/dual-band 3-D FSSs under TE polarization. A double-sided SI loop resonator with via holes is presented for constructing a dual-polarized single band FSS. By adjusting widths of low characteristic impedance sections, the FSS’s band can be expanded into dual bands. Detailed analysis of the coupling between both identical resonators in series is provided for understanding the relationships between subresonators. In addition, the equivalent circuit models are developed to explain the operating principle and analyze parameter effects. The proposed FSS prototype is fabricated and then measured to verify the design methodology. The measured results agree with the simulated data and exhibit a dual-polarized and stable second-order bandstop response under different incident angles up to 30°. The thickness of the structure is 23% of the free-space wavelength at the first center frequency, and the center frequency ratio of both stopbands is only 1.08.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Spurious-Free Dual-Band Bandpass Frequency-Selective Surfaces With Large
           Band Ratio
    • Authors: Da Li;Zhongxiang Shen;Er-Ping Li;
      Pages: 1065 - 1072
      Abstract: Frequency-selective surfaces (FSSs) are widely employed in antenna’s radar cross-sectional reduction, which plays a key role in improving survivability and penetration ability of future military systems. In practical, dual-band bandpass FSSs with large band ratio (BR) are urgently needed for some military equipment, such as homing head, that can detect both middle and far range targets. In this paper, a novel method for designing dual-band bandpass FSS with large BR is proposed. The method can provide a large BR response, by utilizing a spurious-free structure and combing resonant and nonresonant elements. The detailed analysis is presented with the aid of equivalent circuit model as well as closed-form equations to reveal the operating mechanism. A design example is simulated, fabricated, and then measured. Two excellent passbands are obtained with a large BR value of 15.3 in experiment. Moreover, a −10 dB fractional bandwidth of 164.3% is realized from 1.31 to 13.35 GHz, without observing any spurious transmission windows. In conclusion, our proposed method fills the gap of the existing dual-band FSSs to obtain a large BR value of more than 6 and could be a good guidance for designing the future multiband FSSs.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Synthesis Algorithm for Near-Field Power Pattern Control and Its
           Experimental Verification via Metasurfaces
    • Authors: Jun Wei Wu;Rui Yuan Wu;Xi Chao Bo;Lei Bao;Xiao Jian Fu;Tie Jun Cui;
      Pages: 1073 - 1083
      Abstract: Antennas and metasurfaces have enabled a number of far-field manipulation functions. According to the addition theorem of multipoles, near fields have richer spatial spectra than far fields; hence, in the near-field region, it is easier to achieve complex manipulations on field distributions. In this paper, an algorithm is presented to synthesize the near fields of source arrays. Given target distributions of near-field intensities and also predefined source magnitudes, the algorithm will find the needed source phases, which can then be applied on active antenna arrays and passive metasurfaces to induce the target distribution of fields. The algorithm adopts the dyadic Green’s function as the propagator, and hence, it naturally takes account of the near-field and vector properties of electromagnetic fields. As a typical application of the algorithm, an example is given to obtain the excitation phases of a dipole array, which is then physically imitated by a coding metasurface. Experimental measurement is performed and the result proves the validity of the algorithm. From the perspective of information metasurface, the algorithm finds the phase-coding pattern of metasurface to achieve specific functions.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Dynamics of Antenna Reactive Energy Using Time-Domain IDM Method
    • Authors: Debdeep Sarkar;Said M. Mikki;Kumar Vaibhav Srivastava;Yahia M. M. Antar;
      Pages: 1084 - 1093
      Abstract: A general computational paradigm, the time-domain infinitesimal dipole model (IDM) method, is developed and applied to compute reactive energy and radiated power for arbitrary shaped antennas with different time-domain excitations. The proposed technique first utilizes finite-difference time-domain method to compute the time-domain radiating antenna currents from near-zone electric/magnetic fields. Further, the far-zone time-domain radiated power is analytically estimated using a suitable IDM of the antenna spacetime current distributions. The time-domain reactive energy is calculated by adopting a rigorous energy subtraction approach. The proposed time-domain IDM technique is first validated by reproducing the standard antenna-Q-factor results of half-wavelength thin-wire dipoles. Second, time-domain reactive energy signatures are obtained for pulse-excited single and multiband dipole antennas, both in isolated condition and two-element multi-in multi-out (MIMO) topology. Third, the effects of parasitic reflector and director elements on the spatio-temporal energy dynamics of thin-wire Yagi–Uda antennas are demonstrated. The proposed algorithm is very general, applicable to arbitrary antenna shape and spacetime excitations, and hence is expected to enable engineers to look beyond traditional single frequency Q-factors of electrically small antennas to probe into the more fundamental spatio-temporal energy dynamics of general radiating structures, especially future generation 5G MIMO antennas.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Parallel Wideband MLFMA for Analysis of Electrically Large, Nonuniform,
           Multiscale Structures
    • Authors: Stephen Hughey;H. M. Aktulga;Melapudi Vikram;Mingyu Lu;Balasubramaniam Shanker;Eric Michielssen;
      Pages: 1094 - 1107
      Abstract: Electromagnetic scattering from electrically large objects with multiscale features is an increasingly important problem in computational electromagnetics. A conventional approach is to use an integral equation-based solver that is then augmented with an accelerator, a popular choice being a parallel multilevel fast multipole algorithm (MLFMA). One consequence of multiscale features is locally dense discretization, which leads to low-frequency breakdown and requires nonuniform trees. To the authors’ knowledge, the literature on parallel MLFMA for such multiscale distributions capable of arbitrary accuracy is sparse; this paper aims to fill this niche. We prescribe an algorithm that overcomes this bottleneck. We demonstrate the accuracy (with respect to analytical data) and performance of the algorithm for both PEC scatterers and point clouds as large as $755{lambda }$ with several hundred million unknowns and nonuniform trees as deep as 16 levels.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • New Exact Image Methods for Impedance Boundary Half-Space Green’s
           Function and Their Fast Multipole Expansion
    • Authors: Bi-Yi Wu;Xin-Qing Sheng;
      Pages: 1108 - 1118
      Abstract: Two foremost barriers to the development of fast and efficient simulation algorithms for electromagnetic problems in half-space and planar media are efficient Sommerfeld integral evaluation techniques and fast solvers. In this paper, we focus on challenging these two difficulties in the impedance boundary half-space, which is a proper model for common air-lossy media half-space. Based on the Laplace transformation, we first propose an alternative exact image representation for the Sommerfeld integral in half-space Green’s function. In addition to its fast and absolute convergence property, this new exact image version does not contain any singularities and interprets the Sommerfeld integral as an integral over real image line. Furthermore, this representation allows a rigorous fast multipole expansion (FME), and thus it can be applied to the development of fast multipole solver with controllable precision. However, this exact image representation is not valid for the all Sommerfeld integrals in half-space Green’s function. Therefore, a more generalized single mirror image representation, also exact and computationally efficient, is then presented. The strength of the mirror image is obtained through Weyl’s method and steep descent path approach. Subsequently, an approximated FME scheme for this representation is proposed and studied via numerical examples. We find this approximated FME scheme has a higher accuracy than that of previous work. Numerical results show that the proposed work provides exact and efficient evaluations for Sommerfeld integrals in impedance boundary half-space Green’s function and valuable insights into the development of fast multipole solver for half-space electromagnetic problems.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Method of Moments Simulation of Modulated Metasurface Antennas With a Set
           of Orthogonal Entire-Domain Basis Functions
    • Authors: Modeste Bodehou;David González-Ovejero;Christophe Craeye;Isabelle Huynen;
      Pages: 1119 - 1130
      Abstract: A family of orthogonal and entire-domain basis functions (named Fourier–Bessel) is proposed for the analysis of circular modulated metasurface (MTS) antennas. In the structures at hand, the MTS is accounted for in the electric field integral equation (EFIE) as a sheet transition impedance boundary condition on the top of a grounded dielectric slab. The closed-form Hankel transform of the Fourier–Bessel basis functions (FBBFs) allows one to use a spectral domain formulation in the method-of-moments (MoM) solution of the EFIE. Moreover, these basis functions are fully orthogonal, which implies that they are able to represent the global evolution of the current distribution in a compact form. FBBFs also present a better filtering capability of their spectrum compared to other well-known orthogonal families such as the Zernike functions. The obtained MoM matrix is sparse and compact, and it is thus very well-conditioned and can be efficiently computed and inverted. The numerical results based on the proposed decomposition are presented and compared with those based on the use of the Gaussian ring basis functions and with the full-wave analysis of MTS antennas implemented with small printed elements. A very good agreement is observed.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Evaluation of 4-D Reaction Integrals Via Double Application of the
           Divergence Theorem
    • Authors: Javier Rivero;Francesca Vipiana;Donald R. Wilton;William A. Johnson;
      Pages: 1131 - 1142
      Abstract: The use of the method of moments to solve surface integral equations is one of the most popular numerical techniques in electromagnetic modeling and analysis. This method requires the accurate and efficient numerical evaluation of iterated surface integrals over both source and testing domains. In this paper, we propose a scheme for evaluating these 4-D interaction integrals between pairs of arbitrarily positioned and oriented elements. The approach is based on applying the surface divergence theorem twice, once on the source and once on the test domain. When the integrations are reordered as two outer contour integrals plus two inner radial integrals, the initial radial integrations provide significant smoothing of the underlying singular integrands. The method is numerically validated for static and dynamic kernels arising in the electric field integral equation, i.e., for kernels with $1/R$ singularities, and linear basis functions. The proposed formula to evaluate 4-D reaction integrals can be extended to different kernels and to different elements, e.g., to curved or volumetric elements, and to basis functions of higher order.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Geometrical Theory of Diffraction Formulation for On-Body Propagation
    • Authors: Nikolaj Peter Brunvoll Kammersgaard;Søren Helstrup Kvist;Jesper Thaysen;Kaj Bjarne Jakobsen;
      Pages: 1143 - 1152
      Abstract: A geometrical theory of diffraction model for on-body propagation is developed in this paper. The exact solution to the canonical problem of a plane wave incident on an infinitely long cylinder, with arbitrary constitutive parameters, is found. The same is done for a magnetic and an electric infinitesimal dipole source of any orientation, located on the surface of the cylinder. The exact solutions are transformed with the Watson transformation to yield asymptotic expressions that are valid in the deep shadow region. These asymptotic expressions are validated by comparison to the numerically evaluated exact solution. It is found that the expressions are valid as long as the object is opaque, with a geometry down to the size of $({kappa }/{kappa ^{2}+tau ^{2}})> lambda _{0}/2$ , and the rays not too torsional $tau /kappa < 2$ , where $kappa $ and $tau $ are the curvature and torsion of the local geometry, respectively. The asymptotic expressions are found to approximate the exact solution significantly better than the asymptotic expression of an equivalent perfect electric conductor geometry. The same is the case for the impedance boundary condition asymptotic approximation for low dielectric constant materials. Finally, the asymptotic expressions are generalized so they can be applied to any convex geometry of the human body or an opaque lossy dielectric of electrically large size.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Ear-to-Ear Propagation Model Based on Geometrical Theory of Diffraction
    • Authors: Nikolaj Peter Brunvoll Kammersgaard;Søren Helstrup Kvist;Jesper Thaysen;Kaj Bjarne Jakobsen;
      Pages: 1153 - 1160
      Abstract: An ear-to-ear (E2E) propagation model based on geometrical theory of diffraction (GTD) is presented. The model uses the creeping wave loss along the geodesic paths that connect the ears. It is the first model to investigate which geodesic paths that link the ears. The model uses GTD expressions for a lossy dielectric material, which is a much better approximation of the human body than the perfect electric conductor approximation often used. The model is validated for the industrial, scientific, and medical band at 2.45 GHz. The model is valid at any frequency range as long as the propagation loss through the head is significantly higher than the propagation loss around the head. Similarly, the model could be used for other areas of the body. The comparison with simulations shows strong correlation. The antenna orientation and frequency sweeps were performed to further investigate the model. The sweeps change the radiation pattern of the antenna to utilize different paths around the head, but the model still correlates with the simulation. This validates the model’s division of the E2E propagation into different geodesic paths around the head.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Analysis of Joint Channel Coexistence Time at Space-Diversity Radio
           Reception of Meteor Reflections
    • Authors: Amir I. Sulimov;Arkadiy V. Karpov;Sergei A. Kalabanov;Oleg N. Sherstyukov;
      Pages: 1161 - 1169
      Abstract: This paper examines the possibility of joint reception of radio reflections from the same meteor trails simultaneously at two spaced receivers. A refined simulation of a joint reception area (JRA) of meteor radio reflections on the basis of a diffraction theory of oblique scattering of radio waves off ionized meteor trails is performed for radio links of moderate (500 km) and medium (1000 km) lengths. The obtained results may be particularly useful for territory planning of meteor burst communication (MBC) networks with the spatial division of subscribers (SDMA technology). The simulated JRAs also characterize an interception probability of messages. This knowledge is especially important in designing highly secure MBC, such as meteor key distribution systems, intended for the creation of two identical copies of a shared secret key at both sides of the meteor radio link.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Full Hemisphere Aperture-Antenna Far-Field Patterns From Planar Near-Field
    • Authors: Ronald J. Pogorzelski;
      Pages: 1170 - 1179
      Abstract: A simple geometrical estimate resulting from rigorous asymptotic evaluation of the Fourier transform integral leads one to conclude that the angular range of the far-field obtainable using planar near-field measurement techniques is limited by the extent of the scan plane and the separation of this plane from the antenna under test. Here, it is shown that this angular range can be extended to a full hemisphere through proper selection of the measurement parameters and careful treatment of the transform integral. In particular, it is noted that the transverse spectrum of the field can possess singularities. These singularities are spectrally filtered by the finite size of the scan plane resulting in a “muting” effect that must be accounted for in the data processing. This is accomplished through the analytic approximation of the bandlimited singularities. Three hardware examples are shown that demonstrate this more detailed approach comparing the results with corresponding patterns obtained using spherical near-field measurement.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Discrete Environment-Driven GPU-Based Ray Launching Algorithm
    • Authors: Jonathan S. Lu;Enrico M. Vitucci;Vittorio Degli-Esposti;Franco Fuschini;Marina Barbiroli;Jerome A. Blaha;Henry L. Bertoni;
      Pages: 1180 - 1192
      Abstract: We present here a novel, fully discrete ray launching field prediction algorithm that takes advantage of environment preprocessing to efficiently trace rays undergoing both specular and diffuse interactions. The algorithm is “environment driven” because rays are traced from the ray source according to the presence and distribution of obstacles in the surrounding space, therefore adapting ray density to the environment’s characteristics. The environment is discretized into simple regular shapes to facilitate faster geometric computations, to allow for visibility preprocessing and for the algorithm to be parallelized in a straightforward way. These innovative features combined together and implemented on a NVIDIA graphical processing unit (GPU) are shown to speed-up computation by several orders of magnitude compared to more conventional algorithms, while retaining a similar accuracy level. The speed-up and prediction accuracy achieved in reference cases is presented in comparison with a pre-existing ray-based model and RF-coverage measurements.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • $Ka$+ -+and++$Q$+ -Band+Slant-Path+Propagation+Experiments+in+Madrid&rft.title=IEEE+Transactions+on+Antennas+and+Propagation&rft.issn=0018-926X&;&rft.aufirst=Domingo&;José+Manuel+Riera;Pedro+Garcia-Del-Pino;">Time and Orbital Diversity Assessment With $Ka$ - and $Q$ -Band Slant-Path
           Propagation Experiments in Madrid
    • Authors: Domingo Pimienta-Del-Valle;José Manuel Riera;Pedro Garcia-Del-Pino;
      Pages: 1193 - 1201
      Abstract: In satellite communications, the adverse propagation effects produced by the atmosphere to the signal are compensated by the systems using propagation impairment mitigation techniques, protection by diversity being one of their main categories. Two slant-path propagation experiments have been carried out in Madrid in the Ka- and $Q$ -bands, with the Eutelsat KA-SAT and Alphasat satellites, respectively, with three concurrent years of measurements available: from March 2014 to February 2017. In this paper, results on time diversity and orbital diversity—the latter obtained from a frequency scaling approach— are presented, the first one for both frequency bands and the second for the $Q$ -band. An acceptable overall behavior is obtained by comparing the results with the available models. For both diversity techniques, possible gains are moderate but not negligible due to the climatological conditions of the evaluated site.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Scatterer Surface Design for Wave Scattering Application
    • Authors: Fereshteh Samadi;Mohammad Akbari;Mohammad Reza Chaharmir;Abdelrazik Sebak;
      Pages: 1202 - 1211
      Abstract: In this paper, radio wave scattering is considered and an optimal scatterer surface is realized. For this purpose, an ultrawideband and high-efficiency polarization converter unit cell is proposed. Here, the proposed polarization converter unit cell and its mirror are combined to provide 180° phase difference for scattering purposes. The desired combination of unit cells which produces uniform scattering pattern and maximum wave attenuation achieved employing group search optimization (GSO) algorithm. For the problem at hand, the GSO optimization algorithm is presented in bilevel format including master and slave levels. Simulation and experimental results showed that the 10 dB bandwidth of normalized radar cross section (RCS) reduction is achieved in ultrawideband ranging from 5.5 to 20.51 GHz with a fractional bandwidth of 115%, assuring a favorable performance of the proposed method. In addition, a wide-angle bistatic RCS reduction over a wide frequency band is attained.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Through a Cinder Block Wall Refocusing Using SAR Back Projection Method
    • Authors: Vahid Khorashadi-Zadeh;Mojtaba Dehmollaian;
      Pages: 1212 - 1222
      Abstract: Through a cinder block wall imaging using a standard back projection method is studied by employing backscattering in the frequency range of 1–4 GHz. First, using the finite-element method, numerical backscatterings of metallic and dielectric targets behind a cinder block wall are calculated and the effects of the wall on images are investigated. It is shown that the target image is shifted, repeated, and distorted. Second, to refocus the images, the proper Green function is calculated. Basically, the 2-D scattering from a cinder block wall is addressed, analytically and asymptotically. The imaging formulation is modified, using the structure Green function phase. To calculate the Geen function, wall parameters should be evaluated beforehand. Third, to estimate the wall parameters, we proposed the estimation of those using measured wall reflections. Using analytical formulations, direct wall reflections are estimated theoretically and compared with those of measured ones. Using genetic algorithm (GA), wall parameters are extracted, correctly. Having the optimum parameters, the direct wall reflection is effectively subtracted, the Green function is calculated, and the target image is refocused successfully. Finally, using the experimental data, the effectiveness of our proposed approach is demonstrated.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Synchronization of Multiple Independent Subarray Antennas: An Application
           for Angle of Arrival Estimation
    • Authors: Noori BniLam;Jan Steckel;Maarten Weyn;
      Pages: 1223 - 1232
      Abstract: In this paper, we present a new algorithm to synchronize multiple individual receiving subarray antennas to form an augmented array antenna system. This augmented array antenna has a large antenna aperture that can be used for angle of arrival (AoA) estimations and it provides a better AoA estimation accuracy than the individual subarray antennas. The proposed algorithm synchronizes the time and the frequency of the different subarray antennas, using a joint maximum likelihood (ML) optimization for a data-aided received signal. The phase coherency between the subarray antennas is achieved by using a combination of the least mean square and ML algorithms. The experimental results and the simulation example show that the proposed algorithm: 1) is stable in estimating the augmented array antenna pattern; 2) provides more accurate AoA estimations than the individual subarray antennas; 3) has no limitation to the structure of the augmented array antenna in space; and 4) converges very fast. Furthermore, the experimental results prove the feasibility of using AoA estimation techniques for Internet of Things localization in outdoor environments.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Circuit Modeling of a Wireless Power Transfer System by Eigenmode Analysis
           Based on the Impedance Expansion Method
    • Authors: Nozomi Haga;Masaharu Takahashi;
      Pages: 1233 - 1245
      Abstract: The impedance expansion method (IEM), which has been previously proposed by the authors of this paper, is a circuit modeling technique for electrically very small devices. This paper describes a circuit modeling procedure that utilizes the IEM and eigenmode analysis for a wireless power transfer system. First, a multimode circuit model that can represent the higher order resonances in a broadband frequency range is presented. Subsequently, a single-mode circuit model—consisting only of passive elements—that can represent both the radiated and conduction loss powers at approximately its operating frequency band is presented.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Emulation Techniques for Small Scale Fading Aspects by Using Reverberation
    • Authors: Abuu B. Kihero;Murat Karabacak;Hüseyin Arslan;
      Pages: 1246 - 1258
      Abstract: Reverberation chambers (RVCs) are used to provide an efficient and reliable testbed for emulating the wireless channel effects in the laboratory environment. In the literature, various techniques have been studied to enrich the channel emulation capabilities of RVCs. However, insufficient control of some of the emulated channel characteristics (such as time and frequency dispersions) still leaves an open problem for RVC-based channel emulators. In this paper, novel channel emulation techniques by using RVC are introduced to enhance the flexibility in controlling the emulated time and frequency dispersions of the channels. Surface acoustic wave delay lines and power controllers (i.e., amplifiers and attenuators) are used to add degrees of freedom for manipulating the power delay profile during delay spread emulation. This technique also overcomes the challenge of achieving higher delay spread values with benchtop-sized RVC. The second technique is aimed to control the Doppler spectrum shape emulated in the chamber by judiciously placing radio frequency absorbers around the mechanical stirrer. Experimental and mathematical analyses are conducted to evaluate the proposed techniques, and the results show that the proposed methods can improve the channel emulation in the RVCs.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Spherical Open-Resonator Antenna
    • Authors: Kai Lu;Kwok Wa Leung;
      Pages: 1259 - 1264
      Abstract: A broad-beam spherical open resonator (OR) antenna (SORA) is proposed for wireless mobile communications at millimeter-wave bands. The presented SORA, mainly composed of two opposite spherical reflecting surfaces, is excited by an L-probe. The formula for calculating its resonance frequency is given to facilitate the design. The antenna was designed, fabricated, and measured, with reasonable agreement between the measured and simulated results. The measured 10 dB impedance bandwidth and maximum gain are about 4% and 9 dBi, respectively. The SORA is compared with the cylindrical and planar counterparts, and it is found that the OR antenna performance is more stable by adapting the spherical reflectors.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Reflectarray to Generate Four Adjacent Beams per Feed for Multispot
           Satellite Antennas
    • Authors: Daniel Martinez-De-Rioja;Eduardo Martinez-De-Rioja;Jose A. Encinar;Rafael Florencio;Giovanni Toso;
      Pages: 1265 - 1269
      Abstract: This contribution describes a design concept of a reflectarray antenna to produce four adjacent beams per feed through the simultaneous use of polarization and frequency discrimination. The feed position is computed to produce two adjacent beams in different frequencies accounting for the beam squint effect, which ensures a minimum phase variation between the phase distributions at the two frequencies. The other two beams in orthogonal polarization are generated by implementing in the reflectarray a different phase shift for each polarization. This contribution presents the design, manufacturing, and measurement of a 43 cm demonstrator that operates at transmit frequencies in the Ka-band. The proposed concept can be suitable for multiple spot-beam satellites in the Ka-band, enabling a reduction in the number of antennas and feeds needed to provide the multispot coverage.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Electric Field Integral Equation-Based Synthesis of Elliptical-Domain
           Metasurface Antennas
    • Authors: Modeste Bodehou;Christophe Craeye;Isabelle Huynen;
      Pages: 1270 - 1274
      Abstract: A method based on the electric field integral equation is proposed for synthesizing planar metasurface (MTS) antennas built on elliptical apertures. The MTS is modeled with a modulated tensorial surface impedance. Entire-domain basis functions are used to discretize efficiently the currents as well as the surface impedance, allowing a quasi-direct computation of the surface impedance from the desired radiation pattern. The corresponding surface currents are combined with the near-field radiation from a constant reactance to derive the surface impedance of the MTS. The obtained algorithm is, therefore, systematic and can be applied to generate arbitrary radiation patterns, with control on the amplitude, phase, and polarization. Numerical validation of the proposed technique illustrates the effectiveness of the method.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Low-Profile, Dual-Polarized Patch Antenna for 5G MIMO Application
    • Authors: He Huang;Xiaoping Li;Yanming Liu;
      Pages: 1275 - 1279
      Abstract: A dual-polarized patch antenna with an extremely low profile is proposed in this communication. It consists of a main radiator, an annulus, and a reflector. The main radiator contains two pairs of differentially driven feedlines and an irregular patch. These differentially driven feedlines are utilized to coupled feed the irregular patch through a small gap, which has distinguished feature compared with other designs. It turns out that a resonance at 3.55 GHz is generated. Then, an annulus is set above the main radiator to compensate the inductive component induced by the main radiator and generate the other resonant point. As a result, the dual-polarized antenna could work from 3.3 to 3.6 GHz with the extremely compact size of $0.29lambda _{mathbf {0}} times 0.29lambda _{mathbf {0}} times 0.06lambda _{mathbf {0}}$ . ( $lambda _{0}$ is the free-space wavelength at 3.45 GHz.) The simulated isolation and cross-polarization discrimination at 0° of the antenna element reach more than 35 and 44 dB. The simulated front-to-back ratio of co-polarization and cross-polarization is larger than 44 and 22 dB, separately. To verify the design, a prototype of the $2times 2$ array based on the element is fabricated and measured. The results show that the antenna has high potential in the fifth-generation (5G) massive multiple-input multiple-output application.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Miniaturization of Differentially-Driven Microstrip Planar Inverted F
    • Authors: Zijian Shao;Yue Ping Zhang;
      Pages: 1280 - 1283
      Abstract: The modification of a conventional single-ended microstrip planar inverted F antenna (SE-PIFA) into a novel differentially-driven microstrip planar inverted F antenna (DD-PIFA) and the comparison of their performances are first made. It will be shown that the DD-PIFA provides better performance than the SE-PIFA does. Then, the frequency trimming and more importantly the miniaturization of the DD-PIFA are described. A simple formula for determining the resonant frequency of a DD-PIFA is given. Calculated, simulated, and measured results at 2.45 GHz are discussed, indicating the potential applications of the DD-PIFA in high-level integration of radio transceivers for wireless communication systems.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • An SISL Triple-Band Multimode Stacked-Patch Antenna With L-Strips for
           Multiband Applications
    • Authors: Ningning Yan;Kaixue Ma;Haobin Zhang;Pengcheng Jia;
      Pages: 1284 - 1288
      Abstract: A substrate-integrated suspended line triple-band multimode antenna with stacked patch and two L-strips is presented for multiband applications. The two L-strips connected the stacked patch by vias, which can be regarded as a modified step impedance resonator, are introduced for producing two resonant frequencies at 2.45 and 3.6 GHz by means of stimulating dual modes. The two resonant frequencies rely on not only the electrical length but also the impedance ratio. In the higher frequency band, resonant frequencies at 6.1 and 5.25 GHz are generated by the stacked patch and via which connects the feed line and the driven patch, respectively. The measured results reveal that the first band from 2.4 to 2.45 GHz with gain of 4.9 dBi, the second band from 3.52 to 3.6 GHz with gain of 6.2 dBi, and the third band from 5.12 to 6.18 GHz with gain of 10 dBi are acquired. In addition, the radiation patterns with stable property across the whole operating band are obtained.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • An Efficient Preconditioner Based on Adaptive Grouping Technique for
           Multiscale Problems
    • Authors: Chunxian Wang;Zhaoneng Jiang;Mingyue Shui;Ye Jiang;Ting Wan;Xiaofeng Xuan;
      Pages: 1289 - 1293
      Abstract: It is well known that the matrix condition number of discretized formulation for analyzing multiscale objects is very large, because the multiscale objects include the interaction between discrete unknowns in different sizes. The traditional efficient preconditioners for analysis of homogeneous objects are not efficient anymore or cannot be directly extended for the solution of multiscale objects. A good quality compressed block decomposition preconditioner is constructed to speed up the convergence rate of Krylov iterations in this communication by using the adaptive grouping technique. Meanwhile, the multilevel mymargin QR algorithm is utilized to accelerate the matrix-vector product operations. A series of numerical results show that this novel preconditioner is very effective in electromagnetic scattering calculation and can reduce simulation time significantly.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Compact Quasi-Isotropic Dielectric Resonator Antenna With Filtering
    • Authors: Peng Fei Hu;Yong Mei Pan;Xiu Yin Zhang;Bin Jie Hu;
      Pages: 1294 - 1299
      Abstract: A compact quasi-isotropic dielectric resonator (DR) antenna (DRA) with filtering response is first investigated in this communication. The cylindrical DRA is fed by a microstrip-coupled slot, exciting in its ${text {HEM}}_{11 delta }$ mode which radiates like a magnetic dipole. A small ground plane is used for this DRA and it radiates like an electric dipole. The combination of the two orthogonal dipoles leads to a quasi-isotropic radiation pattern, with gain deviation as low as 5.8 dB in the 360° full space. To integrate the filtering function, the microstrip feed-line and the ground plane are turned upside down, and further two stubs with different lengths are used together to excite the DR. Due to the different loading effects of the feeding stubs, two resonances of the DR ${text {HEM}}_{11 delta }$ mode are excited in the passband, effectively enhancing the bandwidth of DRA ( $varepsilon _{r} = 20$ ) to 7%. Furthermore, two controllable radiation nulls are generated by the DR loaded microstrip feed-line, bringing about high frequency selectivity at the edges of the passband and a quasi-elliptic bandpass response. For demonstration, a prototype operating at 2.4 GHz was fabricated and tested; reasonable agreement is obtained between the simulated and measured results.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Experimental Characterization of a Circularly Polarized 1 Bit Unit Cell
           for Beam Steerable Transmitarrays at Ka-Band
    • Authors: Luca Di Palma;Antonio Clemente;Laurent Dussopt;Ronan Sauleau;Patrick Potier;Philippe Pouliguen;
      Pages: 1300 - 1305
      Abstract: We propose here an experimental characterization procedure applied to a 1 bit reconfigurable transmitarray unit cell working in circular polarization (CP) at Ka-band. The transmission phase of the unit cell is controlled on the receiving side by switching two p-i-n diodes integrated on the radiating element. The CP is generated on the transmitting side with a truncated corner patch antenna. A specific waveguide characterization setup and related procedure have been developed to extract the unit cell S-matrix. The proposed setup includes nonstandard waveguide sections, ad hoc transitions, and an orthomode transducer. The experimental results demonstrate a good agreement with full-wave simulations with a discrepancy of less than 0.1 dB on the measured minimum insertion loss of 1.65 dB at 29 GHz. A 3 dB bandwidth larger than 12% has been measured.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Design and Modeling of a Compact Partially Transmissible Resistor-Free
           Absorptive Frequency Selective Surface for Wi-Fi Applications
    • Authors: Chun-Wen Lin;Chi-Kai Shen;Cheng-Nan Chiu;Tzong-Lin Wu;
      Pages: 1306 - 1311
      Abstract: A compact partially transmissible absorptive frequency selective surface (AFSS) which requires neither surface mount device resistors nor resistive ink is proposed in this communication. The resistor-free AFSS utilizes the lossy characteristic of FR-4 substrate material to achieve the absorption property. The method to efficiently model the AFSS based on physical phenomena has been thoroughly discussed, by which the effect of substrate loss can be predicted accurately. An equivalent circuit model is also presented, and its predicted result agrees well with the full-wave simulation. Furthermore, the fabrication and measurement are also conducted to demonstrate the feasibility of resistor-free AFSS. The highest absorption rate of the AFSS is designed around 2.46 GHz, while at least half-power transmission is guaranteed below 1 GHz. These electromagnetic functions as well as the low fabrication cost and complexity make the resistor-free AFSS a promising candidate for advanced packaging and shielding of mixed signal system.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Dual-Polarized, High-Gain, and Low-Profile Magnetic Current Array Antenna
    • Authors: Yijing He;Yue Li;Wangyu Sun;Zhijun Zhang;
      Pages: 1312 - 1317
      Abstract: In this communication, a dual-polarized 36-element ( $3 times 6 times 2$ ) magnetic current array antenna is designed without using complex feeding network. Instead, a pair of differential feeds is adopted to excite the overall dual-polarized array within a low profile. Such a simple feeding strategy is achieved by using the TM90 mode of a microstrip antenna, which is loaded by $3 times 4$ identical half-wavelength slots for each polarization. In this configuration, an in-phase $3 times 6$ element single-polarized magnetic current array is achieved for high gain, but with narrow bandwidth due to the high-order mode. By trivially 90° rotating and combining, the proposed dual-polarized, high-gain, and low-profile magnetic current array is designed, constructed, and measured. Within a total size of $2.92lambda _{0}times 2.92lambda _{0}times 0.085lambda _{0}(lambda _{0}$ is the free-space wavelength at the center frequency), the measured maximum gain is 15.5 dBi, also with the merits of low profile, low sidelobes, simple feeding, and high port isolation, exhibiting promising usage in MIMO and diversity applications.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Dual-Polarized Band-Absorptive Frequency Selective Rasorber Using
           Meander-Line and Lumped Resistors
    • Authors: Weiliang Yu;Guo Qing Luo;Yufeng Yu;Yujian Pan;Wenhui Cao;Yujian Pan;Zhongxiang Shen;
      Pages: 1318 - 1322
      Abstract: A novel dual-polarized band-absorptive frequency selective rasorber (FSR) is proposed in this communication. The FSR is constructed by two-layer cascaded printed circuit boards, in which meander-line square loops with and without lumped resistors loaded on the top and bottom surfaces of the two substrates. Its operating principle is analyzed, and an accurate equivalent circuit model is presented. A prototype has been fabricated, assembled, and measured. The measured absorption band is from 4.8 to 6.81 GHz (34.6%), with a thickness of $lambda _{mathrm {a}}$ /8 at 4.8 GHz. Moreover, it is almost transparent to electromagnetic waves below 1.54 GHz. The measurement results achieve a good agreement with the simulated results, which verifies the effectiveness of the design.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Compact High-Performance Lens Antenna Based on Impedance-Matching
           Gradient-Index Metamaterials
    • Authors: Na Zhang;Wei Xiang Jiang;Hui Feng Ma;Wen Xuan Tang;Tie Jun Cui;
      Pages: 1323 - 1328
      Abstract: A planar wavefront transformation lens based on gradient-index metamaterials is proposed. The designed lens is composed of isotropic and inhomogeneous metamaterials and can reach impedance matching with free space. Based on the impedance-matching metamaterial lens, we present a compact high-gain and high-aperture-efficiency horn-based lens antenna working from 8 to 12 GHz. At the center working frequency of 10 GHz, the performance of the antenna is significantly improved and the measured gain increases to 17.7 dBi, which is 6.5 dBi higher than that of the original H-plane horn antenna. The half-power beamwidth and sidelobe level in the H-plane reduces to 6.2° and 15.3 dB, respectively, and the aperture efficiency reaches 94%. Such performance is much better than that of the conventional optimal H-plane horn antenna.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Metamaterial-Inspired Self-Polarizing Dual-Band Dual-Orthogonal Circularly
           Polarized Fabry–Pérot Resonator Antennas
    • Authors: Chunling Chen;Zhen-Guo Liu;Hao Wang;Yongxin Guo;
      Pages: 1329 - 1334
      Abstract: This communication presents a Fabry–Pérot resonator antenna (FPRA) with the dual-band dual-orthogonal circular polarization (CP). The whole FPRA consists of a linearly polarized (LP) microstrip patch antenna and a chiral metamaterial (CMM) superstrate. The LP microstrip antenna serves as the feed system, while the CMM superstrate has the function of polarization transformation. The CMM also works as a partial reflective sheet to form an FPRA. The ray-tracing method in the circular base is introduced to describe the mechanism of this type of FPRA. Furthermore, the procedure of controlling the frequency ratio of two bands is discussed as well. An antenna prototype is fabricated to validate the simulated results. In the frequency band from 7.24 to 7.36 GHz, the proposed FPRA produces right-handed CP wave. However, left-handed CP wave is achieved when the frequency ranges from 7.96 to 8.14 GHz. The realized gains reach 12.98 dBic at 7.28 GHz and 13.25 dBic at 8 GHz, respectively.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Single Slot Antenna With Multiple Radiation Modes Using a Parasitic Loop
    • Authors: Yaohui Yang;Zhiqin Zhao;Xiaoxiang Ding;Zaiping Nie;Qing-Huo Liu;
      Pages: 1335 - 1340
      Abstract: In order to increase radiation modes for slot antennas, a new method of loading a parasitic loop pair is proposed. By adding switches to control the open- or closed-state of each loop, the loop pair works at four states, generating multiple radiation modes. Consequently, besides the original bidirectional broadside mode, two additional directional radiation modes are generated, radiating to endfire. As a result, a simple slot antenna could work in multiple radiation modes with the proposed method; meanwhile, no much-increased size or complicated structure is needed. Thus, a single slot antenna can be employed to meet the requirement for multifunction and multienvironment applications. To demonstrate this design concept of using the parasitic loop pair, an antenna structure is designed and fabricated. One parasitic loop is formed by connecting two printed metallic strips with copper shorting pins; p-i-n diode switches and bias circuits are inserted to control the state of the two loops with dc signals. Both measured and simulated results indicate that the proposed parasitic loop pair is effective in providing multiple radiation modes for slot antennas.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Compact Circularly Polarized Wearable Button Antenna With Broadside
           Pattern for U-NII Worldwide Band Applications
    • Authors: Xiaomu Hu;Sen Yan;Guy A. E. Vandenbosch;
      Pages: 1341 - 1345
      Abstract: A novel circularly polarized button antenna is proposed. The antenna is constructed on a disk-shaped FR-4 substrate. This disk is located on the top of a textile layer and supported by a feeding probe. The antenna works in the 5.47–5.725 GHz Unlicensed National Information Infrastructure worldwide band, with over 14% relative impedance bandwidth and over 7% relative axial ratio bandwidth. A prototype has been fabricated and measured. A good agreement is found between measured and simulated results.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • 2-D Electromagnetic Scattering and Inverse Scattering From
           Magnetodielectric Objects Based on Integral Equation Method
    • Authors: Tian Lan;Na Liu;Yanhui Liu;Feng Han;Qing Huo Liu;
      Pages: 1346 - 1351
      Abstract: Efficient 2-D full-waveform forward and inverse electromagnetic scattering solvers are presented in this communication. The combined field volume integral equation (CFVIE) is formulated in a layered medium. Different from the previous work, the mixed-order basis function is adopted in the discretization of the 2-D CFVIE. Meanwhile, the permittivity and permeability are simultaneously reconstructed in the inversion through the variational Born iteration method, which is enhanced with a self-adaptive regularization factor and applied to the multifrequency data. The proposed forward solver is validated by comparisons with the finite-element simulations.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Mutual Coupling Reduction of Slot Antenna Array by Controlling Surface
           Wave Propagation
    • Authors: Jeet Ghosh;Debasis Mitra;Shouvick Das;
      Pages: 1352 - 1357
      Abstract: In this communication, we present a methodology to reduce mutual coupling in a planar slot antenna array by using electric metamaterial. The proposed methodology is based on resisting and steering the propagation of surface wave. Initially, an array of complementary split-ring resonator (CSRR) is designed between the two slots for suppressing the surface wave propagation. Afterward, to steer the surface wave propagation, complementary fishnet structures are designed on the two sides of the slot array. Finally, for a better level of isolation improvement, both CSRR and complementary fishnet structures are simultaneously used. The final design has achieved at least 14 dB improvements in isolation level throughout the wide operating bandwidth of around 2 GHz, even if the gap between the slots is only 3.4 mm. The efficiency and the realized gain of the proposed antenna have also been studied. Because of the use of both metamaterial structures as a complementary, the overall configuration becomes fully planar and easy to realize.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A Compact Reconfigurable Microstrip Antenna With Multidirectional Beam and
    • Authors: Guang-Wei Yang;Jianying Li;Bao Cao;Dujuan Wei;Shi-Gang Zhou;Jingya Deng;
      Pages: 1358 - 1363
      Abstract: In this communication, a novel pattern and polarization reconfigurable microstrip antenna with a simple structure is presented. By switching four p-i-n diodes integrated with the antenna, the current distribution on the antenna can be altered, thereby changing the antenna performance. The proposed antenna can realize eight operating states of the radiation patterns including one boresight linear polarized (LP) pattern with narrow beamwidth, one boresight LP pattern with wide beamwidth, four directional LP patterns in the xoz plane and yoz plane, and one left-hand circularly polarized and one right-hand circularly polarized pattern with wide beamwidth. The operating frequency band of the antenna is from 3.1 to 3.45 GHz. An antenna prototype has been fabricated to validate the design concept. Good agreement between the simulated and measured results is found, and the cross polarization level is below −21 dB.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Closed Form Solution to the Incident Power of Gaussian-Like Beam for
           Scattering Problems
    • Authors: Guangwen Pan;Lisha Zhang;
      Pages: 1364 - 1367
      Abstract: To avoid edge diffraction induced by surface truncation in the method of moments, the Gaussian-like beam is used as the incident source. Such a wave, also referred to as “tapered wave,” provides concentrated power density near the scattering center and decays rapidly to negligible level before reaching the edge for most of the incident angles. The resulting scattered intensities need to be normalized by the tapered incident power, to quantitatively predict the radar cross section, which is compatible to the far-zone plane wave results from measurements and analytical solutions. Conventionally, the incident power of tapered wave has been computed numerically by summing up the scattered fields of a flat surface over all azimuth angles, which is tedious and inefficient. In this communication, an exact expression of the incident power is analytically elaborated as an onefold definite integral of zero to one. The binomial expansion of this analytical method is also outlined, and the validation data show good agreement between the analytical solution and numerical results.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Wideband, Low-Profile Patch Array Antenna With Corporate Stacked
           Microstrip and Substrate Integrated Waveguide Feeding Structure
    • Authors: Jun Xu;Wei Hong;Zhi Hao Jiang;Hui Zhang;
      Pages: 1368 - 1373
      Abstract: In this communication, a corporate stacked microstrip and substrate integrated waveguide (SIW) feeding structure is reported to be used to broaden the impedance bandwidth of a $4 times 4$ patch array antenna. The proposed array antenna is based on a multilayer printed circuit board structure containing two dielectric substrates and four copper cladding layers. The radiating elements, which consist of slim rectangular patches with surrounding U-shaped parasitic patches, are located on the top layer. Every four radiation elements are grouped together as a $2 times 2$ subarray and fed by a microstrip power divider on the next copper layer through metalized blind vias. Four such subarrays are corporate-fed by an SIW feeding network underneath. The design process and analysis of the array antenna are discussed. A prototype of the proposed array antenna is fabricated and measured, showing a good agreement between the simulation and measurement, thus validating the correctness of the design. The measured results indicate that the proposed array antenna exhibits a wide $vert text {S}_{11}vert < -10$ dB bandwidth of 17.7%, i.e., 25.3–30.2 GHz, a peak gain of 16.4 dBi, a high radiation efficiency above 80%, and a good orthogonal polarization discrimination of higher than 30 dB. In addition, the use of low-profile substrate in the SIW feeding network makes this array antenna easier to be integrated directly with millimeter-wave front-end integrated circuits. The demonstrated array antenna can be a good candidate for various Ka-band wireless applications, such as 5G, satellite communications and so on.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • A UHF RFID Tag Embeddable in Small Metal Cavities
    • Authors: Andrea Michel;Vittorio Franchina;Paolo Nepa;Alfredo Salvatore;
      Pages: 1374 - 1379
      Abstract: A compact in-metal ultrahigh frequency radio frequency identification tag for identification of metal components is described. The radiating element is printed on a $23times 23 times 1$ mm3 copper-clad alumina (Al2O3) substrate ( $varepsilon _{mathbf {r}} = 9$ , tan $delta = 0.0003$ ) and consists of two rectangular quarter-mode patch antennas properly arranged to make the tag performance as robust as possible even when the tag is embedded in small cavities carved out of metal objects. The entire structure has been optimized by taking into account the presence of a thin superstrate of commercial epoxy resin used to protect the tag. The effect of the cavity size on the tag performance is numerically analyzed. Measurements on a tag prototype are also described and discussed.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Aperture Illumination Designs for Microwave Wireless Power Transmission
           With Constraints on Edge Tapers Using Bezier Curves
    • Authors: Xun Li;Kwai Man Luk;Baoyan Duan;
      Pages: 1380 - 1385
      Abstract: A new method is proposed for the antenna aperture illumination design on microwave wireless power transmission. Bezier curves are used to describe the aperture amplitude distributions. By optimizing the coordinates of the associated Bezier points, an aperture distribution yielding the maximum beam collection efficiency (BCE) can be achieved. Moreover, edge tapers can be easily controlled by the Bezier curves. The proposed method shows its effectiveness from carrying out extensive numerical experiments on different Fresnel parameters as well as edge taper constraints. The results show that larger aperture power coefficients obtain with a little sacrifice of BCEs when larger edge taper constraints are considered. Besides, the peak lobe irradiated outside the rectenna can be suppressed as well.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Wireless Cloaking System Based on Time-Reversal Multipath Propagation
    • Authors: Shuai Ding;Yong Fang;Jin-Feng Zhu;Yu Yang;Bing-Zhong Wang;
      Pages: 1386 - 1391
      Abstract: In this communication, we present a new method of encoding /decoding information contained in a wave packet using multipath effect. A signal is mixed with an auxiliary signal and sent into an enclosed cavity. The strongly distorted signal transmitted through the cavity is then sent to a receiver, where it is time reversed and sent to a second enclosed metallic cavity that is strictly identical to the first one. As a result, the waveform of the initial signal is reconstructed at a point of the second cavity that is equivalent to the point of the first cavity due to the spatial and temporal focusing. Using the mechanism, secure wireless data transmission is carried out. Finally, the impact of the size of the cavity on intersymbol interference and the frequency dispersion caused by frequency selective fading are discussed. Such a communication system ensures a high level of security.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
  • Call for Papers Recent Advances in Metamaterials and Metsurfaces
    • Pages: 1392 - 1392
      Abstract: Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers.
      PubDate: Feb. 2019
      Issue No: Vol. 67, No. 2 (2019)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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Fax: +00 44 (0)131 4513327
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