Recent Articles
-
Gain Enhancement and Sidelobe Level Reduction of Microstrip Patch Antenna Under Operation of TM50-Like Mode
31 May 2024 Renan A. Santos, Helton S. Bernardo, Danilo H. Spadoti, Guilherme S. da Rosa and Rafael A. Penchel propose a microstrip patch antenna (MPA) operating in the TM50-like mode, designed for gain enhanced and sidelobe levels (SLLs) reduction. The methodology involves altering the resonator’s surface current distribution by introducing three groups of transverse slots at points of null electric field. Additionally, two symmetrically positioned stubs are utilized to the antenna’s gain enhanced. They verify that proper combinations of such artifacts on the proposed radiators significantly reduce the SLL while maintaining the high-gain characteristics of the TM50-like mode. A prototype was fabricated and characterized for operation around 7.6 GHz, in the C band.
-
Electromagnetic-Informed Generative Models for Passive RF Sensing and Perception of Body Motions
30 May 2024Stefano Savazzi, Federica Fieramosca, Sanaz Kianoush, Michele D’Amico and Vittorio Rampa discuss two popular techniques, namely Variational Auto-Encoders (VAEs) and Generative Adversarial Networks (GANs), and their adaptations to incorporate relevant electromagnetic (EM) body diffraction methods. The proposed EM-informed GNN models are verified against classical EM tools driven by diffraction theory, and validated on real data. The paper explores emerging opportunities of GNN tools targeting real-time passive RF sensing in communication systems with dense antenna arrays. Proposed tools are also designed, implemented, and verified on resource constrained wireless devices.
-
RF Circuit Analysis of UWB Planar Log Periodic Antenna for 5G Communications Using Theory of Characteristic Modes
08 May 2024 P. Sumithra, Mohammed Gulam Nabi Alsath, K. J. Jegadishkumar and D. Kannadassan present the systematic RF analysis, fabrication, and equivalent circuit modeling for sub-6GHz 5G application using theory of characteristic modes (TCM). The fabricated pLPA is designed to cover the 5G bands with a high gain of >5 dBi and a fractional bandwidth of >1. Using simulation tool based on method of moments, radiating and non-radiating modes are tracked and studied with detailed physics. These modes are modeled using analytically derived equivalent circuit and assembled in an RF/microwave circuit simulator.
-
Refinements to the Design of Traveling-Wave Waveguide Slot Arrays
03 May 2024 Jacob C. Coetzee presents a new design approach to traveling-wave waveguide slot arrays that not only ensures that sidelobes specifications are met, but also achieves good impedance matching and high efficiency. The procedure is demonstrated using a 21-element array in standard X-band waveguide and performance is validated though both simulation and measurement.
-
Ultra-Wideband Phased Antenna Array Time Delay Unit Architecture Optimization in Presence of Component Non-Idealities
01 May 2024 Daniel A. Ramirez, W. Joel D. Johnson and Gokhan Mumcu investigate the recently reported time delay unit architecture (TDU-A) optimization method based on integer linear programming for practical implementation of ultra-wideband (UWB) phased antenna arrays (PAAs). Specifically, the method is considered for linear UWB PAAs and their feed networks which include non-idealities when practical implementations of their circuit components are pursued. These non-idealities are shown to cause additional time delay errors that were unaccounted for in prior work. The errors are induced by frequency dependent variations in power divider isolation and load mismatch, component VSWRs, and dispersion.
-
Experimental Phase-Encoded Linear Sampling Method Imaging With a Single Transmitter and Receiver
25 April 2024 Matthew J. Burfeindt, Hatim F. Alqadah and Scott Ziegler evaluate the phase-encoded linear sampling method (PE-LSM) using experimental data. They collect synthetic aperture data in an anechoic chamber using only a single transmit-receive channel. With the aid of a monostatic-to-multistatic transform, they generate reconstructions of each target via the PE-LSM. The results evince significant improvements in fidelity to the true target geometries compared to imagery generated by both conventional LSM processing and a conventional backprojection-based radar approach.
-
Synthesis and Design of 3-D Microwave Absorber With 70° Angular Stability for C-Band and X-Band
22 April 2024 Tian-Xi Feng, Lei Zhu and Hui Li present the synthesis and design of 3-D microwave absorber with 70° angular stability for C-band and X-band. The operating principle is firstly investigated, where the absorber is considered as an energy convertor. With the help of our proposed universal equivalent transmission line (TL) model, the absorptive performance can be accordingly synthesized. Then, a design method for efficient absorption under large angles is presented. By selecting a proper synthesized angle (SA), the angular stability can be effectively improved.
-
Miniaturized Design of Dual Transmission Frequency Selective Rasorber With Wide Angular Stability
28 March 2024 Mehran Manzoor Zargar, Archana Rajput and Kushmanda Saurav propose a miniaturized design of dual transmission frequency selective rasorber (FSR) with absorption-transmission-absorption-transmission (A-T-A-T) feature. Initially, low frequency resonators are incorporated on the square ring shaped lossy resistive layer for expanding the broad absorption towards the lower spectrum of frequency. Then the dual bandpass frequency selective surface (FSS) with transmission bands lying within the absorption spectrum is integrated with the resistive layer. Further, a cross-loop resonator is integrated inside the square ring of the resistive layer due to which a dual transmission pole is achieved through the resistive layer aligning with the dual operating frequencies of bandpass FSS.
-
Cusp Phased Metasurfaces for Wideband RCS Reduction Under Broad Angles of Incidence
15 December 2023 Mustafa K. Taher Al-Nuaimi, William G. Whittow, Guan-Long Huang and Rui-Sen Chen presents an efficient and effective design approach of the phase distribution calculation across metasurface for significant radar cross section (RCS) reduction of a circular polarization (CP) and liner polarization (LP) radar waves. The RCS reduction using the proposed design approach is achieved by imposing a novel cusp phase mask (which is usually used to generate 3D self-accelerating and self-healing cusp beams) at each geometric phased anisotropic unit cell composing the proposed cusp phased metasurface.
-
A Step-by-Step Design Methodology for Broadband Tunable Microwave Metasurface Absorbers Using Theory of Characteristic Modes
29 November 2023 Zihao Ning, Mengmeng Li, Dazhi Ding, Xia Ai, Jiaqi Liu and Chao-Fu Wang develop a characteristic mode (CM)-based design methodology for the reconfigurable microwave metasurface absorbers (MMA) with using commercially available substrates. Theoretical intrinsic connection between modal behaviors and absorption properties is first formulated for the design of the structures. As a proof of the method, a broadband MMA consisting of butterfly elements is step-by-step designed. The positions and values of the impedance loading are determined based on the modal significances and modal currents for broadband operation. The absorption performance is evaluated by the formulated theoretical model and verified by full-wave simulation.