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IEEE Antennas and Wireless Propagation Letters
Journal Prestige (SJR): 1.047
Citation Impact (citeScore): 4
Number of Followers: 89  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1536-1225
Published by IEEE Homepage  [228 journals]
  • IEEE Antennas and Wireless Propagation Letters Publication Information

    • Free pre-print version: Loading...

      Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Compact Wideband Dual-Polarized Antenna Using Monolithic Dielectric for
           5G Base Station Application

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      Authors: Yan-Yuan Zhu;Jianpeng Wang;Jian-Xin Chen;Wen Wu;
      Pages: 1717 - 1721
      Abstract: A compact wideband dual-polarized dielectric resonator antenna (DRA) is investigated in this letter. The antenna is formed by a monolithic cross-shaped dielectric block with a rectangular part for support and two pairs of orthogonal metal strips printed on the bottom of the cross dielectric. For demonstration, a dual-polarized prototype antenna with the electrical size of 0.38 λ0 × 0.38 λ0 × 0.14 λ0 has an impedance bandwidth of 16.5% from 3.25 to 3.85 GHz with |S11| < −15 dB covering the N78 band for fifth-generation (5G) new radio. Furthermore, the antenna has a stable gain of 8.5 ± 0.4 dBi across the operating frequency range, demonstrating the high stability of the radiation characteristic for the two radiation modes. All the simulated and measured results for the DRA are given, showing a good agreement.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Beam Scanning for Dual-Polarized Antenna With Active Reflection
           Metasurface

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      Authors: Yongtao Jia;Guangsheng Jiang;Ying Liu;Yichen Zhong;
      Pages: 1722 - 1726
      Abstract: In this letter, a dual-polarized antenna with steerable beam is presented. The antenna consists of an active reflection metasurface and a cross dipole antenna. The beam scanning of the antenna is obtained by tuning the capacitance of the varactor diodes mounted on the active reflection metasurface cell. A reflection phase covering 300° can be obtained by tuning the capacitance value. The air layer in the middle of the reflection unit makes the reflection phase curve flat and achieve a stable phase difference over a wide band. Moreover, the cross-shaped structure of the reflection unit can manipulate the reflection phase of the electromagnetic waves with two polarizations. Therefore, the dual-polarized antenna can maintain good radiation performance and port isolation while the beam is deflected. The simulated radiation efficiency is higher than 88%. The measured results demonstrate that the beam-steering range is ±20°, short for voltage standing wave ratio (VSWR) is less than 1.7 and the port isolation is greater than 20 dB in the frequency range of 3.3–3.6 GHz.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Rectangular Waveguide-Fed Surface-Wave Frequency-Scanning Antenna
           Utilizing Wavevector Mismatch

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      Authors: Luyi Wang;Hongyu Shi;Xiaoming Chen;Jianjia Yi;Liang Dong;Haiwen Liu;Anxue Zhang;Zhuo Xu;
      Pages: 1727 - 1731
      Abstract: In this letter, we propose a design of rectangular waveguide-fed surface-wave frequency-scanning antenna utilizing the principle of wavevector mismatch. First, the transition from a side-fed rectangular waveguide mode to spoof surface plasmon polariton (SSPP) is achieved. Then the SSPP propagating on the metal-dielectric interface is modulated through wavevector mismatching that induces the SSPP to spatial radiating wave conversion. Theoretical deduction proves the frequency scanning nature of the generated radiating beam. Phase gradient metasurface (PGM) is used to realize the wavevector engineering that causes artificial wavevector mismatch. Simulated and experimental results, agreeing well with each other, showed that the antenna can realize beam scanning from −8° to 11.6° across 6.8 to 7 GHz, with realized gain varying from 5 to 5.98 dBi.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Hybrid Chebyshev Approximation Technique and Subdomain AIM Method for
           Wideband RCS Computation

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      Authors: Hao-Xuan Gong;Xing Wang;Chun-Heng Liu;Hai-Rong Zhang;Xiang-Gang Ma;
      Pages: 1732 - 1736
      Abstract: An efficient hybrid method based on subdomain adaptive integral method (SAIM) and Chebyshev approximation technology (CAT) is proposed for analyzing the wideband radar cross section (RCS) of complex multiscale objects in this letter. The SAIM cannot only be used to effectively deal with the difficulty of slow convergence caused by the mutiscale problems, but also greatly reducing the computational memory. By introducing the CAT into SAIM, we can use the currents at a few frequency sampling points to predict the currents at any frequency point over the entire band. In addition, the application of the Maehly approximation can obtain a better accuracy. Numerical examples show that the proposed SAIM-CAT can significantly improve the calculation efficiency without loss of accuracy.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Dual-Band Circularly Polarized Annular Ring Patch Antenna for GPS-Aided
           GEO-Augmented Navigation Receivers

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      Authors: Sahana C;Nirmala Devi M;Jayakumar M;
      Pages: 1737 - 1741
      Abstract: A compact, single- feed, dual band, circularly polarized annular ring patch antenna coupled to a cross slot is proposed in this letter for GPS-aided GEO-augmented navigation (GAGAN) receivers covering L band, centered at 1176.45 MHz (L5) and 1575.42 MHz (L1) frequencies. The antenna consists of two annular rings configured by two small strips, which is coupled to a cross slot in the ground plane for gain enhancement. Circular polarization in both the bands is produced by introducing perturbations in outer annular ring and two orthogonal strips in the center space of inner annular ring. The proposed CP antenna radiates LHCP in both the desired frequencies. Two shorting pins are introduced near the feed to improve impedance matching. The simulated and measured reflection coefficient, gain, circular polarization, and axial ratio are in accord with each other. The measured 10 dB bandwidth is 2.7% (1168–1200 MHz) for the L5 and 2.5% (1560–1600 MHz) for L1. The AR bandwidth below 3 dB for the designed antenna is 1.5% (1156–1174 MHz) for L5 and 1% (1556–1572 MHz) for L1.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Parasitic Effect Suppression With Resonance Cancelation for Broadband
           Absorber/Reflector

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      Authors: Sai Guo;Zhanglong Mao;Shimin Hu;Haoran Li;Zhaowang Cao;Xiao Ji;Ling Miao;Jianjun Jiang;
      Pages: 1742 - 1746
      Abstract: This letter exhibits a switchable double-sided absorber/reflector that realizes broadband performance. This structure effectively breaks the limitation of the absorption bandwidth due to the parasitic capacitance of the p-i-n diode through resonance cancelation. First, the LC parallel resonance is adapted to inhibit the interference of the parasitic capacitance by connecting the inductance in parallel with the p-i-n diode. Then, a gap capacitance is introduced to increase the resonance frequency and further expand the bandwidth. The double-sided design is applied to avoid the short-circuit phenomenon caused by the parallel connection of the inductor and the p-i-n in the single-sided design. To control the inductance value more precisely, the meander inductor is employed. Finally, the reflectivity of the proposed structure covers broadband of 3.91–9.77 GHz from reflection to below −10 dB under normal incidence by changing the working states. Furthermore, a sample of the proposed structure was manufactured and measured. The measurements are consistent with simulations.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Design of a Broadband High-Gain Omnidirectional Antenna With Low Cross
           Polarization Based on Characteristic Mode Theory

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      Authors: Chen Fu;Chunjie Feng;Wubo Chu;Yutao Yue;Xiaobo Zhu;Wenhua Gu;
      Pages: 1747 - 1751
      Abstract: A low-profile, high-gain, and low cross-polarization omnidirectional antenna is proposed. The antenna structure is pretty concise with convenient probe feeding and sandwich-structure design. The characteristic mode analysis shows that the antenna can excite quasi-TM01 and quasi-TM02 modes in a broadband and, thus, results in monopole radiation mode and low cross polarization in a broad operating band. The full-wave simulation and experiments were performed to verify the antenna design. The fabricated prototype antenna showed
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Improved A-EFIE System for Electromagnetic Simulation in Low Frequency
           Regime

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      Authors: Wen-Jing Chen;Sheng Sun;Yang Liu;Lijun Jiang;Jun Hu;
      Pages: 1752 - 1756
      Abstract: In this letter, the quasi-Helmholtz projectors are applied to address numerical cancellation of augmented electric field integral equation (A-EFIE). The projectors rescale the term $overline{bf V} cdot i{k}_0{bf j}$ and right-hand side to guarantee that the solution is stable at very low frequency. The improved system is full rank without removing the singularity caused by charge neutrality. Compared to the EFIE with quasi-Helmholtz projectors, this letter presents a better convergence performance and takes less computational cost. The numerical results show that the solution of both scattering problems and circuit problems can ensure the accuracy in the low-frequency regime.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Intelligent Reflecting Surface-Assisted Interference Mitigation With Deep
           Reinforcement Learning for Radio Astronomy

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      Authors: Junhui Peng;Hailin Cao;Zahid Ali;Xiaodong Wu;Jin Fan;
      Pages: 1757 - 1761
      Abstract: Radio frequency interference (RFI) is a significant threat to astronomical observations. Thus, this letter exploits the intelligent reflecting surfaces (IRSs) to mitigate RFI by adjusting the reflection coefficients of IRSs. Aiming to synthesize a spatial quiet zone in the control area of a radio telescope, an optimization problem for joint multiple reflected beamforming at IRSs is formulated. As the interference behavior and direction are dynamic, an IRS relative position encoding attention deep deterministic policy gradient (RPEA-DDPG) learning algorithm is proposed to jointly optimize the reflected beamforming of IRSs without the knowledge of the interference model. Simulation results demonstrate that the proposed technique can effectively establish an open electromagnetic field quiet zone to prevent RFI from entering the receiver.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Conformal Array Antenna for Applications in Wide-Scanning Phased Array
           Antenna Systems

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      Authors: An Li;Shi-Wei Qu;Shiwen Yang;
      Pages: 1762 - 1766
      Abstract: A dipole with four branches, fed by Marchand balun, is designed to be conformal with wing of an unmanned aerial vehicle. With the help of branches, the proposed dipole element achieves a better impedance matching performance. Meanwhile, the metallic coupled strip is added to move the scanning blindness out of the operating frequency band, without deterioration at broadside radiation. Besides, the beamwidth in the vertical plane, i.e., the H-plane of the dipole, can be effectively compressed by loading three metallic strip directors, and the element gain increases as well. Based on the dipole element, a 12-element linear phased array is designed and simulated. The simulated results show that the array achieves ±60° scanning range in the horizontal plane, with the voltage standing wave ratio lower than 2.5 in the operating band of 2.4∼3 GHz. Moreover, the 3 dB beamwidth in the H-plane is 81° at the center frequency of 2.7 GHz. The measured results of the fabricated antenna prototype agree reasonably well with the simulated ones, which verify the feasibility of the wing-conformal linear phased array design.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Electrically Small Circularly Polarized Antenna Based on Capacitively
           Loaded Loop

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      Authors: Shuxuan Liu;Zhan Wang;Yuandan Dong;
      Pages: 1767 - 1771
      Abstract: This letter presents a novel design of an electrically small, circularly polarized (CP), capacitively loaded loop (CLL)-based antenna for UHF radio frequency identification (RFID) applications. A simplified CLL working as a magnetic dipole is proposed. It is analyzed by the equivalent circuit and field distribution. Owing to the strong LC-resonant character of the CLL structure, an electrically small size of 0.137 λ0 × 0.137 λ0 × 0.046 λ0 (ka = 0.67) is easily achieved. Two sets of CLL structures with different loop dimensions are orthogonally arranged, with the crossed slot and 45°-rotated coupling feedlines. As a result, the dual-mode operation is realized and the RHCP wave is radiated. A 3.71% measured −10 dB impedance bandwidth (899–933 MHz) is achieved, which is well poised for the 902–928 MHz UHF reader applications. The measured peak gain and radiation efficiency are 4.83 dBic and −1.26 dB (74.8%), respectively. The proposed electrically small CLL-based CP antenna exhibits excellent overall performance, including easy fabrication, good bandwidth, high gain and efficiency and wide beamwidth. Therefore, it is suitable for RFID reader applications and other Internet of Things (IoT) systems.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Low-Cost High-Gain Filtering Patch Antenna With Enhanced Frequency
           Selectivity Based on SISL for 5G Application

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      Authors: Tong Wang;Ningning Yan;Mi Tian;Yu Luo;Kaixue Ma;
      Pages: 1772 - 1776
      Abstract: This letter presents a high-gain filtering antenna with multiple radiation nulls and enhanced frequency selectivity using substrate integrated suspended line (SISL) technology. The presented antenna is composed of driven patches with slots, parasitic units, stubs, and stacked patches. The first radiation null is caused simultaneously at the upper band edge when the stacked patches are introduced to produce a resonance mode. The second radiation null is produced by the slots on the driven patches at the lower band edge. Due to the TM20 mode of the driven patches, the third radiation null is introduced at higher frequency. Owing to the stubs and parasitic units, the fourth radiation null is caused at lower frequency. The above four radiation nulls achieve excellent filtering performance with high selectivity. The measured results indicate the outstanding performance of the filtering antenna. The passband is from 3.28 to 3.79 GHz, perfectly covering the 5G-N78 band. The peak gain reaches 11.14 dBi, and the out-of-band rejection level is 17.8 dB. In addition, this filtering patch antenna is designed based on low-cost substrate FR4.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Combined ITM and LITU-R Model for Enhanced Radio Coverage Predictions of
           Mission-Critical Communications in Mountainous Vegetated Terrains

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      Authors: Nuno Leonor;Stefânia Faria;Mário Vala;Rafael F. S. Caldeirinha;
      Pages: 1777 - 1781
      Abstract: This letter presents a combined model for appropriate radio coverage of mission-critical push-to-talk communications in mountainous vegetated terrains. The proposed model uses the irregular terrain model (ITM) with the detailed information of the ground topography to predict the excess loss caused by the terrain irregularities, along with the Lateral International Telecommunications Union of Radio model, to account for the excess loss caused by the presence of vegetation in the radio path. The performance of the proposed combined model was assessed against experimental results obtained from a measurement campaign conducted along unpaved paths and trails, usually taken by firefighters during firefighting procedures, in mountainous terrains with dense vegetation. The acquired experimental data was assessed against experimental results obtained from a measurement campaign conducted along unpaved paths and trails.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Polarization Converter Surface Integrated MIMO Antenna for Simultaneous
           Reduction of RCS and Mutual Coupling

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      Authors: Priyanka Das;Kaushik Mandal;
      Pages: 1782 - 1786
      Abstract: This letter provides an effective solution to deal with the radar cross section (RCS) and mutual coupling of the multiple-input–multiple-output (MIMO) antenna simultaneously. A wideband reflective type polarization converter (PC) is designed and its strategic placement in between the antenna elements of the two-element MIMO antenna has been conceived to mitigate these two issues concurrently. The antenna elements of the proposed MIMO antenna are placed at a proximal distance of 0.088 λ from each other. The proposed MIMO architecture ensures a maximum coupling reduction of 46 dB compared to the conventional MIMO across 4.4–8 GHz. The PC surface reduces the reflection of copolarized waves and enhances cross-polarized reflection. A supercell formed by a unit cell of PC and its 90° rotated counterpart causes phase cancellation of cross- polarized reflected waves, which contributes to wideband RCS reduction by a maximum value of 7 dB. The alignment of PC cells in a column between the adjacent antenna elements causes a reduction in the mutual coupling due to introduction of an extra coupling path and cross-polarization conversion. A good agreement between the simulated and measured results validates this concept of the proposed MIMO design with low RCS and mutual coupling.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Compact Wideband Pattern Diversity Antenna for 5G-NR Applications

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      Authors: Shuxuan Liu;Zhan Wang;Wei Sun;Yuandan Dong;
      Pages: 1787 - 1791
      Abstract: In this letter, a novel compact wideband antenna with broadside and conical diversity patterns is presented for fifth-generation (5G)-NR applications. The capacitive loading is implemented to enhance the port isolation and for size reduction (0.35 λ0 × 0.29 λ0 × 0.047 λ0). With an extra slot mode introduced by the coupled feeding scheme, a wide impedance bandwidth is obtained. A miniaturized broadband 180° hybrid coupler is designed to provide in-phase and out-of-phase excitations. It is composed of a quarter-wavelength parallel coupled-line and lumped LC components. As a result, conical and broadside diversity radiation patterns are achieved. The proposed antenna is analyzed, fabricated, and measured. Good agreement is achieved between the simulated and measured results. The measured overlapped −10 dB impedance bandwidth is 20.5% (3.16–3.81 GHz). The measured in-band isolation is better than 22.7 dB and the peak value achieves 34.7 dB. The proposed pattern diversity antenna exhibits good overall performance, including compact size, wide bandwidth, high isolation, and good radiation performance. Therefore, it is suitable for space-limited 5G-NR applications.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Dual-Band Beam-Scanning Antenna at Ka-Band by Rotation of Two
           Transmitarrays

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      Authors: Peipei Wang;Wu Ren;Qingyun Zeng;Zhenghui Xue;Weiming Li;
      Pages: 1792 - 1796
      Abstract: A dual-band beam-scanning antenna by rotation of two transmintarrays (TAs) operating at 20 and 30 GHz has been presented in this letter. TA's unit cell has three metal layers and demonstrates almost completely independent performance at two frequency bands. Two designed TAs have unit cells of different sizes to achieve dual-band with different linear phases. By rotating the two TAs synchronously around the axis orthogonal to the planes of the TAs, it enables two-dimensional (2-D) beam scanning with maximum scanning angles of ±40°. The achieved simulated peak gains are 19.9 dBi, 20.5 dBi and 22.5 dBi, 23.2 dBi at phi = 0°, phi = 90° at 20 and 30 GHz, respectively. The maximum beam scanning losses are 1.7 dB, 2.6 dB and 1.5 dB, 2.7 dB. Moreover, the two beams at the two frequencies can basically point to the same direction at the same time. To validate the design, a prototype is fabricated and tested. The measured results are in good agreement with the simulated results.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Geometry-Based Clustering Characteristics for Outdoor Measurements at
           28–30 GHz

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      Authors: Guojin Zhang;Jesper Ødum Nielsen;Xuesong Cai;Gert Frølund Pedersen;Wei Fan;
      Pages: 1797 - 1801
      Abstract: This letter presents an analysis of channel characteristics for an outdoor scenario at the frequency band of 28–30 GHz. A geometry-based clustering algorithm is proposed to group the measured multipath components (MPCs) from the interaction points on the surrounding walls or objects according to ray-tracing three-dimensional (3-D) simulations, giving results that are more physically interpretable than the traditional clustering algorithms. The cluster-level characteristics at 15 positions along a predefined route covering both line-of-sight (LoS) and non-LoS (NLoS) scenarios are investigated. Moreover, power contributions of MPCs with multiple bounces (up to seven bounces in NLoS scenario) from the interaction objects are also investigated.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • TM Scattering by a Shallow Elliptical-Shaped Cavity

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      Authors: Mehdi Bozorgi;Saeed Reza Ostadzadeh;
      Pages: 1802 - 1806
      Abstract: In this letter, the problem of electromagnetic scattering by a shallow elliptical-shaped cavity in a perfect electric conductor plane is considered. We propose an efficient modal approach based on the region-matching technique that can calculate scattered fields without the use of the Mathieu functions. By enforcing boundary conditions at a semicircular auxiliary border, a system of linear equations is constructed. The results obtained by this method are compared with those provided by the method of moment. Finally, the effect of the shape of the cavity on the scattering signature is investigated.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Using the Interpolative Decomposition to Accelerate the Evaluation of
           Radome Boresight Error and Transmissivity

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      Authors: Jinbo Liu;Chen Yang;Mang He;Jin Yuan;Zengrui Li;
      Pages: 1807 - 1811
      Abstract: Based on the method of moments, the interpolative decomposition (ID) technique is extended to accelerate the evaluation of radome boresight error (BSE) and transmissivity, which belongs to electromagnetic radiation problems with the right-hand side (RHS) matrix containing multiple vectors. Because the RHS matrix from radiation problems has many null rows, the matrix can be first reduced to a compressed form, then decomposed by the ID technique to figure out the skeleton RHS vectors by exploiting its rank-deficient property. Iterative solutions are only executed for these skeleton vectors, followed by the restoration process to obtain the full solutions. Compared with the existing ID methods designed for scattering problems, the proposed ID method is much easier to implement and companied with a high solution efficiency. Numerical experiments are performed on an antenna array enclosed by a radome to evaluate the BSE and transmissivity, illustrating the performance and accuracy of the proposed method.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Performance-Enhanced Absorbing Boundary Condition for FDTD Methods on
           Face-Centered Cubic Grids

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      Authors: Xinsong Wang;Guangzhi Chen;Shunchuan Yang;Yaoyao Li;Wanli Du;Donglin Su;
      Pages: 1812 - 1816
      Abstract: Based on the auxiliary differential equation (ADE), a performance-enhanced convolution perfectly matched layer (CPML) for the face-centered cubic finite-difference time-domain (FCC-FDTD) method is developed in this letter. Unlike the traditional FDTD methods on Yee’s grids, for which the CPML technique is relatively straightforward to be implemented, poor performance, and even instability may occur in the FCC-FDTD method. To avoid these problems, the ADE technique is incorporated into the derivation, and the impact of node locations on absorbing boundary constitutive parameters is carefully considered. In addition, the derivation of the time-marching formulations is substantially simplified. The optimal ranges of constitutive parameters are found through a numerical sweep. Two numerical examples, the electromagnetic pulse propagation and absorbed power density of a brain model during mobile communication, are examined to validate the performance. The results suggest that the proposed ADE-CPML for the FCC-FDTD method shows good stability and accuracy.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Fast Analysis of Bistatic Scattering Problems for Three-Dimensional
           Objects Using Compressive Sensing and Characteristic Modes

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      Authors: Zhonggen Wang;Pan Wang;Yufa Sun;Wenyan Nie;
      Pages: 1817 - 1821
      Abstract: In this letter, a combination of characteristic mode (CM) and compressive sensing (CS) is utilized to accelerate the solution of bistatic scattering problems of three-dimensional (3-D) objects. The surface induced currents discretized by Rao–Wilton–Glisson basis functions are successfully sparsely transformed by CM basis functions based on domain decomposition. Different from the dense matrix equation of traditional method of moments (MoM), a low-rank CS model with smaller size is constructed in the proposed method, wherein the induced currents can be reconstructed efficiently. Due to partially filling of the impedance matrix and efficient recovery algorithm, the time cost in the proposed method is reduced dramatically. Last, the results from several numerical simulations validate the efficiency and accuracy of the proposed method.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Comparison of MB-CBFM and Modified ASED Basis Function Method to Analyze
           Interconnected Finite Periodic Arrays

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      Authors: Ping Du;Wei Xiang;Song-Song Zhu;
      Pages: 1822 - 1826
      Abstract: This letter compares the macro block-characteristic basis function method (MB-CBFM) with the modified accurate subentire-domain (ASED) basis function method to solve the interconnected finite periodic arrays. In the MB-CBFM, a compressed matrix equation whose size is less than that of the conventional CBFM can be obtained using the idea of macro blocks and the array theory. In the modified ASED method, a few sets of ASED bases on the cells are constructed by solving the subarray problem excited by the several plane waves. Afterwards, a reduced matrix equation will be obtained. The size of the matrix is greater than that in the MB-CBFM for the large-scale arrays. Numerical results obtained from the modified ASED basis function method are more accurate than those of the MB-CBFM.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Hybrid Waveguide Feed Network for Aperiodic Subarray Beamforming

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      Authors: Dae Woong Woo;Kyunghyun Oh;Deok Kyu Kong;
      Pages: 1827 - 1831
      Abstract: In this letter, a hybrid waveguide feed network for an aperiodic subarray beamforming antenna is presented. The feed structure is divided into vertical and horizontal parts. Vertical parts have inclined slots with a reduced-height waveguide, and the horizontal part has unequal H-plane septum power dividers to achieve a compact feed network with acceptable electrical characteristics. The angle of each inclined slot and the position of each septum were designed for amplitude weighting and in-phase characteristics. For comparison, a simple resonant feed network without septum power dividers (i.e., with waveguides and inclined slots) was simulated to access the effectiveness of the proposed network. The proposed structure was fabricated using computer numerical control milling and diffusion bonding. The input reflection coefficient was less than −15 dB, and the transmission phase difference between 20 ports was less than 72° within a bandwidth of 2.4%. This feed network design has potential applications in electronically scanned arrays and subarray antennas for a limited field of view.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Low-Cost Antenna Using SISL Technology With Suppressed Sidelobe Level
           for 77 GHz Automotive Radar

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      Authors: Xihui Teng;Kaixue Ma;Ningning Yan;Yu Luo;
      Pages: 1832 - 1836
      Abstract: The letter proposes a substrate integrated suspended line low-cost antenna with suppressed sidelobe levels for 77 GHz automotive radar. The antenna consists of two embedded air cavities. The double-layer wiring with dielectric excavation makes more electromagnetic energy distributed in the air cavity, significantly reducing the dielectric loss. The sidelobe level is decreased to −15 dB according to the Chebyshev synthesis. The measured results validate that the antenna bandwidth is from 75.01–82.12 GHz which can cover the 77 GHz application (76–81 GHz) with the max realized gain of 13.5 dBi. In addition, the antenna is fabricated on the FR4 substrates resulting in low cost.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Research on Accurate OTA Testing for Large-Form-Factor 5G IoT Devices in
           Medium-Sized Anechoic Chamber

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      Authors: Meijun Qu;Kai Zhang;Siyang Sun;
      Pages: 1837 - 1841
      Abstract: This letter focuses on whether accurate over-the-air (OTA) performance of large-form-factor (LFF) Internet-of-Things (IoT) devices (especially for vehicles) can be obtained from medium-sized anechoic chambers (ACs). For LFF IoT devices under test (DUTs), antenna locations are usually deviated significantly from the center of the OTA testing system due to mechanical positioner or chamber constraints in medium-sized ACs, which will lead to distortion for assessed OTA performance. This work evaluates the effect of offsetting the antenna under test integrated in LFF IoT DUTs from the center of the quiet zone on OTA integrated-type quantities. A new figure of merit ROFF has been defined to characterize the off-center extent, while the influence of which on OTA performance as well as associated simulations is presented based on statistical analysis. It can be found that the performance deviation is determined by ROFF rather than absolute off-center distance. The relationship between ROFF and performance deviation can be derived by using the least-squares fitting method. Additionally, it is acquired that for off-center scenario, performance deviation cannot be eliminated by increasing measurement grid density, yet can be reduced significantly by introducing off-center correction.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Planar Frequency Selective Surface-Based Switchable Rasorber/Absorber for
           Airborne Application

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      Authors: Rahul Dutta;Jeet Ghosh;Abhishek Sarkhel;
      Pages: 1842 - 1846
      Abstract: In this letter, a switchable frequency selective surface is designed that can operate between rasorber and absorber having a wide passband characteristics. The structure has an extra advantage of being built on a single dielectric layer having lossy and lossless layer on the two opposite sides. The lossy layer comprises of lumped resistors, which assists in wideband absorption from 4.8 to 15 GHz. PIN diodes are mounted in the lossless layer to equip the structure with rasorber/absorber operation. Under the rasorber operation, a wide transmission bandwidth in between the absorption band from 9 to 11 GHz is obtained. The system is also simplified with the help of an equivalent circuit model. The structure is carefully designed so that it is immuned to polarization and angle sensitivity. Finally, the prototype is fabricated and measured, and the results are found to be in good agreement with the simulated ones. The proposed design is expected to find its application in all airborne technologies.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • FPGA Acceleration of Matrix-Assembly Phase of RWG-Based MoM

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      Authors: Tomasz Topa;Artur Noga;Tomasz P. Stefański;
      Pages: 1847 - 1851
      Abstract: In this letter, the field-programmable gate array (FPGA) accelerated implementation of matrix-assembly phase of the method of moments (MoM) is presented. The solution is based on a discretization of the frequency-domain mixed potential integral equation using the Rao–Wilton–Glisson basis functions and their extension to wire-to-surface junctions. To take advantage of the given hardware resources (i.e., Xilinx Alveo U200 accelerator card), nine independent processing paths/runtime efficient compute units are developed and synthesized. Numerical results provided for a quadrifilar spiral antenna mounted on a conductive handset box show that the proposed parallelization scheme performs 9.53× faster than a traditional (i.e., serial) central processing unit (CPU) MoM implementation, and about 1.67× faster than a parallel six-core CPU MoM implementation.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Computationally Efficient Millimeter-Wave Scattering Models: A Combined
           Blockage and Backscattering Model

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      Authors: Adrián Lahuerta-Lavieja;Martin Johansson;Christina Larsson;Ulf Gustavsson;Guy A. E. Vandenbosch;
      Pages: 1852 - 1856
      Abstract: Blockage and backscattering by objects are relevant phenomena in millimeter-wave propagation. Conventionally, these phenomena are treated by means of separate models and, in turn, included in the total channel response. In this letter, we propose a combined model for calculating both blocked and backscattered fields from planar smooth electrically-large rectangular surfaces. The contributions of this letter are twofold: first, a single formulation for calculating both blocked and backscattered fields; and second, backscattering models are proposed for calculating blockage as well. Furthermore, the proposed model can be implemented using several models and, finally, is validated with electromagnetic simulations and measurements. Due to its computational efficiency, the model can be suitable for system- and link-level simulations of wireless systems, particularly when Monte Carlo simulations are applied.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Monopole and Dipole Hybrid Antenna Array for Human Brain Imaging at 10.5
           Tesla

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      Authors: Myung Kyun Woo;Lance DelaBarre;Matt Waks;Russell Lagore;Jerahmie Radder;Steve Jungst;Chang-Ki Kang;Kamil Ugurbil;Gregor Adriany;
      Pages: 1857 - 1861
      Abstract: In this letter, we evaluate antenna designs for ultra-high frequency and field (UHF) human brain magnetic resonance imaging (MRI) at 10.5 tesla (T). Although MRI at such UHF is expected to provide major signal-to-noise gains, the frequency of interest, 447 MHz, presents us with challenges regarding improved B1+ efficiency, image homogeneity, specific absorption rate (SAR), and antenna element decoupling for array configurations. To address these challenges, we propose the use of both monopole and dipole antennas in a novel hybrid configuration, which we refer to as a mono-dipole hybrid antenna (MDH) array. Compared to an 8-channel dipole antenna array of the same dimensions, the 8-channel MDH array showed an improvement in decoupling between adjacent array channels, as well as ∼18% higher B1+ and SAR efficiency near the central region of the phantom based on simulation and experiment. However, the performances of the MDH and dipole antenna arrays were overall similar when evaluating a human model in terms of peak B1+ efficiency, 10 g SAR, and SAR efficiency. Finally, the concept of an MDH array showed an advantage in improved decoupling, SAR, and B1+ near the superior region of the brain for human brain imaging.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Low-Profile Dual-Polarized Luneburg Lens Based on TE/TM Surface
           Wave Modes

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      Authors: Tianqi Ao;Yongsheng Pan;Yuandan Dong;
      Pages: 1862 - 1866
      Abstract: This letter presents a novel dual-polarized two-dimensional (2-D) Luneburg lens operated at millimeter-wave band with a low-profile and planar structure. Based on a dual-mode unit cell that supports TE/TM surface wave modes with orthogonal polarizations, the proposed 2-D Luneburg lens with gradient refractive index distribution compresses the beamwidth in one dimension and achieves fan-shaped beams for both of the two polarization modes. To verify the proposed Luneburg lens, a prototype is fabricated using the printed circuit broad process with low cost, weight, and profile. The measured peak gain of H- and V-pol mode is 17.0 dBi and 17.2 dBi, respectively. Because the surface wave modes are applied to both polarizations of the proposed Luneburg lens, the electromagnetic waves transform from the lens to the air smoothly, without the need for additional radiation structures, which reduces the profile further and increases the antenna aperture.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Phase Turbulence Prediction Method for Line-of-Sight
           Multiple-Input–Multiple-Output Links Caused by Atmospheric Environment

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      Authors: Rui Zhang;Shoubao Zhang;Zhenwei Zhao;Zhensen Wu;Changsheng Lu;Leke Lin;
      Pages: 1867 - 1871
      Abstract: The multiple-input–multiple-output (MIMO) phase of the received signal is the most important parameter in the line-of-sight MIMO (LOS MIMO) system. The MIMO phase turbulence often occurs in practical applications, and the LOS MIMO system cannot operate normally in severe cases. However, there is no practical MIMO phase prediction method presently. A tropospheric radio-duct during phase turbulence was observed using a mesoscale numerical weather prediction (NWP) model. In this study, a novel MIMO phase prediction method was proposed. In the method, the tropospheric refractivity profile was predicted using a mesoscale NWP model, and then MIMO phase was predicted by the parabolic equation model. The comparison of the predicted MIMO phases with the measured results shows good agreement. MIMO phase turbulence prediction method can provide support for LOS MIMO system performance prediction.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Compact Ultrawideband Frequency Selective Rasorber With Hybrid 2-D and
           3-D Structure

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      Authors: Kun Xue;Huiqing Zhai;
      Pages: 1872 - 1876
      Abstract: A compact ultra-wideband frequency selective rasorber (CUWFSR) with hybrid two-dimensional (2-D) and 3-D structure is proposed in this letter. The wide absorption band is obtained by the multiple resonances excited by two dipole resonators and the hybrid structure. By inserting split-ring resonator into the short dipole to bypassing the losses in the passband, an FSR with an internal transmission window and ultrawideband absorption performance is finally realized. The proposed rasorber shows a fractional bandwidth of 140.8% with a transparent window from 14.2–15.8 GHz. Then an improved design which involves two approaches of bypassing the losses of the lossy layer is also provided. Finally, an FSR with a middle passband at 15 GHz and a fractional bandwidth of 137.3% for the absorption rate better than 90% is achieved. The prototype of the improved CUWFSR is fabricated and measured for validation.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • On the Enforcement of Electric Field Boundary Condition in the Moment
           Method Solution of Volume-Surface Integral Equation

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      Authors: Jinbo Liu;Xumeng Men;Hui Zhang;Zengrui Li;Jiming Song;
      Pages: 1877 - 1881
      Abstract: When the volume-surface integral equation (VSIE) is used to model the composite objects, the electric field boundary condition (BC) can be explicitly enforced on the dielectric-perfect electric conductor (PEC) interfaces to reduce the volumetric unknowns. In the proposed BC-based VSIE, using the least-square method, one of the four coefficients of SWG basis functions belonging to a same tetrahedron terminated by a PEC triangle is directly calculated by the other three, which is no longer a volumetric unknown. The matrix equation generated by the method of moments is iteratively solved in a straightforward manner, which can be accelerated by the multilevel fast multipole algorithm. Through reliable numerical results, it is illustrated that the enforcement of the BC can reduce the memory usage and the number of iterations without compromising accuracy, in addition to good versatility.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Beam-Scanning Printed Dipole Antenna Fed by a Rectangular Patch With
           Periodic Structures

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      Authors: Yuming Wei;Yuanxin Li;Zhixi Liang;Shao Yong Zheng;Yunliang Long;
      Pages: 1882 - 1886
      Abstract: In this letter, a beam-scanning printed dipole antenna fed by a rectangular patch with periodic structures is proposed. A simple rectangular patch embedded with rampart line structures is used as the novel feeding structure for the planar dipole. The embedded rampart line structures are used to reduce the size and radiation of the rectangular patch, which facilitates feeding. By exciting the coupled modes of the dipoles, continuous and gradual phase differences for the dipole arms can be achieved so as to achieve beam scanning. A double-layer reflector and director are used to enhanced the antenna gains. In the simulated results, the dipoles radiated a beam that scanned from −48° to 14° in the azimuth planes as frequency changed. The measured results show consistent scanning beams within the operating bands from 3.16 to 3.24 GHz. The measured gain ranged from 3.27 to 5.58 dBi within the corresponding bands. Furthermore, the proposed antenna had a high radiation efficiency close to 90%, as well as a compact size.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • $_{1/2,0}$ +Mode+Planar+Copolarized+Microstrip+Antenna+for+Full-Duplex+Systems&rft.title=IEEE+Antennas+and+Wireless+Propagation+Letters&rft.issn=1536-1225&rft.date=2022&rft.volume=21&rft.spage=1887&rft.epage=1891&rft.aulast=Srivastava;&rft.aufirst=Kahani&rft.au=Kahani+Kumari;Mondeep+Saikia;Rahul+Kumar+Jaiswal;Sudha+Malik;Kumar+Vaibhav+Srivastava;">A Compact, Low-Profile Shorted TM $_{1/2,0}$ Mode Planar Copolarized
           Microstrip Antenna for Full-Duplex Systems

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      Authors: Kahani Kumari;Mondeep Saikia;Rahul Kumar Jaiswal;Sudha Malik;Kumar Vaibhav Srivastava;
      Pages: 1887 - 1891
      Abstract: In this letter, a single-layer compact copolarized shorted TM1/2,0 mode microstrip patch antenna is presented for in-band full-duplex application. Two shorted TM1/2,0 mode patch antennas, used for transmission and reception purposes, make the structure compact. The wideband behavior of the patch antenna is obtained by fusing the two resonances, one because of the shorted TM1/2,0 mode radiating patch and the other because of the λ/4 line resonator. To enhance the isolation between the transmitter and receiver antenna, a novel defected ground structure is used. Slots are introduced into the ground plane to create a weak field region for the basic antenna element. The other antenna element (receiver) is located in the weak field region to enhance isolation. Further enhancement in isolation is achieved by introducing a T-shaped metallic strip into the slots. The structure is proposed with the credits of compactness, enhanced bandwidth, colinear polarization, very less fabrication complexity, low profile, and high isolation. The proposed structure is fabricated and measured. The structure experimentally exhibits a bandwidth (≤ −10 dB) of 2.42–2.52 GHz with the isolation of 25 dB, peak isolation of 36 dB, and an average realized gain of 4 dBi in the entire band.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Antenna Loading by Passive Impedance for Linear-to-Circular Polarization
           Conversion

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      Authors: Luis Felipe Fonseca Dias;Camille Jouvaud;Christophe Delaveaud;Hervé Aubert;
      Pages: 1892 - 1895
      Abstract: Many passive and wireless devices, such as RFID tags or batteryless wireless sensors, are designed to control electromagnetic field backscattered by the devices, in order to maximize the interrogation range (or the device-to-reader separation distance) and/or to mitigate the electromagnetic clutter. In this letter, we show that a linearly polarized (LP) electromagnetic field can be converted into a circularly polarized field by using a passive and chipless device. The device, also called tag, consists of a one-port antenna loaded by a passive impedance, whose value is derived from a rigorous electromagnetic model including structural and antenna scattering modes. The experimental validation of predicted linear-to-circular polarization conversion is reported in the case of a patch antenna illuminated by a LP field. At the operating frequency of 2.6 GHz, the measured axial ratio of the electric field backscattered by the tag is lower than 1 dB.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Ultrathin and Simple 3-D Rasorber Based on Ferrites With Embedded
           Epsilon-Near-Zero Waveguides

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      Authors: Shuomin Zhong;Jiaqi Feng;Zi-Wei Zheng;Yungui Ma;
      Pages: 1896 - 1900
      Abstract: An ultrathin and simple three-dimensional (3-D) frequency-selective rasorber with a passband located between two absorption bands is proposed. The absorption bands are obtained by employing commercial magnetic materials in the absorption channel and the passband is realized using epsilon-near-zero tunneling waveguides. The attractively ultrathin and simple feature is achieved by utilizing tunneling effect at the cutoff frequency of metallic waveguides with arbitrary length, permitting the overall thickness shrink into the same as that of the absorber. A prototype with a thickness of only 0.108 λc (λc is the free-space wavelength at the transmission frequency) is fabricated and measured, exhibiting a transmission band with −3 dB fractional bandwidth (FBW) of 35.7% and a minimum insertion loss of 1 dB, and an FBW of 135.6% for reflection coefficient less than −10 dB. The lumped-components-free and lithography-free features greatly facilitate the fabrication, which is promising in practical low-cost applications.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Enabling MIMO Antenna Miniaturization and Wide Circular Polarization
           Coverage by Amalgamation of a Dielectric Strip Between Meandered Traces
           and Slotted Ground

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      Authors: Shahanawaz Kamal;Mohd Fadzil Ain;Ubaid Ullah;Mohamad Faiz Mohamed Omar;
      Pages: 1901 - 1905
      Abstract: This letter presents a dual-element multiple-input–multiple-output antenna for applications in the very high frequency band. A compact geometry of microstrip line-fed radiators engaging 0.04 $ times $ 0.04 ${{boldsymbol{lambda }}}^2$ footprint at 150 MHz was fabricated on an FR-4 substrate and tested in the anechoic chamber. Good circularly polarized radiation patterns were generated by employing two corner-fed meander lines and integrating slots at strategic locations of the ground. A dielectric strip was stacked above the substrate and between the two meandered elements to enable $ -$10 dB impedance bandwidth of 24%. In the operating frequency band from 133 to 169 MHz, the proposed antenna offered axial ratio of -25 dB, gain of $sim $3 dBi, efficiency (${boldsymbol{eta }}$) of $sim $80%, envelope correlation coefficient of $ < $0.5 and diversity gain of $sim $10 dB.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Efficient Mutual-Coupling Aware Fault Diagnosis of Phased Array Antennas
           Using Optimized Excitations

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      Authors: Prajosh K P;Sreekar Sai Ranganathan;Francesco Ferranti;Uday K Khankhoje;
      Pages: 1906 - 1910
      Abstract: Antenna fault diagnosis for phased antenna arrays is an important research area since faulty elements deteriorate the expected field pattern, leading to degraded performance in various applications. While several compressive sensing-based techniques have been proposed, they rely on a simplified array factor formula, ignoring mutual coupling effects among antennas. We show that this assumption can lead to poor diagnosis in the presence of significant mutual coupling by using two popular models—the average embedded element pattern and a port-level coupling matrix approach. Also, we optimize the antenna excitations to minimize the mutual coherence of the system measurement matrix, leading to a reduced number of measurements required for fault diagnosis. Our simulation results indicate that accounting for the effect of mutual coupling results in a far more reliable diagnosis. In addition, our framework is executed using a single measurement probe fixed in space, thus making a step toward practical fault diagnosis techniques that can be deployed on antenna array systems.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Characterization Techniques for Reconfigurable Reflectarray Unit Cells at
           240 GHz

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      Authors: Susanne Brandl;Mario Mueh;Adrian Diepolder;Ekaterina Kunakovskaya;A. Çağrı Ulusoy;Christian Damm;Christian Waldschmidt;
      Pages: 1911 - 1915
      Abstract: Reflectarrays and tunable surfaces receive increasing attention for wavefront engineering in the upper millimeter-wave range. As chip-based phase shifters can now be integrated with antenna elements, the performance verification at unit cell (UC) level is of great interest for a cost-efficient investigation of large-scale arrays. In this article, two UC designs with integrated phase shifter and on-chip antenna are evaluated experimentally at 240 GHz. For the first time, a single element is characterized above 100 GHz by applying the classic waveguide simulator technique. Since this method is mechanically problematic at high frequencies due to small dimensions and mechanical tolerances, an alternative approach involving a near-field probe is presented and investigated. The results for both measurement methods are compared and interpreted, assisted by full-wave simulations.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Textile Fixed-Frequency Pattern-Reconfigurable Coupled-Mode
           Substrate-Integrated Cavity Antenna

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      Authors: Jie Cui;Feng-Xue Liu;Lei Zhao;Wenbin Dou;
      Pages: 1916 - 1919
      Abstract: A textile fixed-frequency pattern-reconfigurable coupled-mode substrate-integrated cavity (CMSIC) antenna is designed for wearable applications. The H-plane beam directions of the basic CMSIC antenna in the odd and even modes are theoretically deduced. Metallic snap buttons are added at the radiation apertures as switches. Simulations indicate that changing the state of the buttons leads to the shift of the odd- and even-mode resonance frequencies, and thus leads to the mode/pattern reconfiguration at 2.45 GHz. A textile prototype is fabricated using the computerized embroidery and is measured to validate the design. The influences of human body and bending conditions are investigated through simulations and measurements.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • A Fast Method for SBR-Based Multiaspect Radar Cross Section Simulation of
           Electrically Large Targets

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      Authors: Hao Wang;Bing Wei;Hongwei Liu;
      Pages: 1920 - 1924
      Abstract: In this letter, a novel method is proposed to rapidly simulate the multiaspect monostatic radar cross section of electrically large complex targets based on the shooting and bouncing ray method (SBR). The core of the method is to use the inheritance of the illumination to determine the illumination of the target surface, rather than independently simulating for each required aspect angle as in the traditional SBR method. To achieve this, the illumination variation on the target surface is summarized and the genetic illumination information is defined. The error of the method is also discussed and the multiple precalculation solutions is proposed to control the error. Different simulation examples show our method has good general applicability and great efficiency. Finally, a realistic aircraft is simulated at 10 GHz using the multiple precalculation solution.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
  • Broadband Fixed-Beam Leaky-Wave Antenna With Consistent and High Gain
           Based on Ridge Gap Waveguide

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      Authors: Hang Du;Zheng Li;Junhong Wang;
      Pages: 1925 - 1929
      Abstract: In most communication scenarios, antennas are often required to achieve broadband and directional radiation, and beam squint with frequency is unfavorable for broadband signal transmission. The traditional leaky-wave antennas (LWAs) have beam squint with frequency. In this letter, an LWA with fixed beam direction in a broadband is designed with consistent gain over the band. A ridge gap waveguide (RGW) is adopted to construct a nondispersive structure, and one lateral side is connected to a parallel plate filled with dielectric slab. Thus, leakage radiation is produced at the interface between the RGW and the parallel plate, generating a beam with fixed direction and high gain. The novelty is that in theory the fixed beam can be realized in infinite band owing to the nondispersive waveguide. Finally, a broad band of up to 58% (from 22 to 40 GHz) is achieved due to the limitations of the stopband structure and feeding port. The measured beam is fixed at 41° over the whole band, with a slight beam deviation of 2.6°. The realized gain is consistent over the band with a peak gain of 19.3 dBi. The designing method provides a simple and efficient way to realize the broadband fixed-beam LWAs.
      PubDate: Sept. 2022
      Issue No: Vol. 21, No. 9 (2022)
       
 
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