Recent Articles
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Going Beyond a Simple RIS: Trends and Techniques Paving the Path of Future RIS
31 January 2024 Kinza Shafique and Mohammad Alhassoun review recent developments in reconfigurable intelligent surfaces (RIS) technology with a special emphasis on tuning techniques, hardware concepts, RIS empowered by artificial intelligence techniques, and applications for next generation of networks. Finally, a viewpoint on the difficulties and potential directions of intelligent metasurfaces are also presented.
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Ultra-Wideband Antennas for Wireless Capsule Endoscope System: A Review
17 January 2024 Ben Li, Yifan Wang, Junchi Zhao and Jingjing Shi present a comprehensive review of different ultra-wideband UWB antenna designs for wireless capsule endoscopy (WCE) system. In-body and on-body UWB antennas are classified according to the radiative performances and structure. Particular attention is also paid to the models used in simulation and experiment, as well as some key performance parameters and technologies in the process of antenna design. This extensive summary of UWB antennas for WCE systems will help to understand the prospects and challenges in this field.
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4×4 UWB Phased Array Antenna With >51° Far-Field Scanning Range for Wireless Power Transfer Application
02 January 2024 Adnan Basir Patwary and Ifana Mahbub design a single unit antenna to achieve ultrawideband (UWB) operation while maintaining high gain and unidirectional radiation pattern. It determines the array element spacing based on the theoretical modeling and simulation and measurement based validation to achieve the highest gain, minimum coupling coefficient, and lower side lobe level (SLL). In order to achieve beam steering, each 2×2 subarray is considered as a single quadrant thus dividing the 4×4 phased array antenna into four quadrants where all 16 single elements are individually fed. The far-field radiation beam is steered by controlling the phase difference between each quadrant.
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Analytical Equations for Designing Meander Line Antennas
01 January 2024 Ngu War Hlaing, Kamilia Kamardin, Yoshihide Yamada, Takuji Arima, Masaharu Takahashi and Naobumi Michishita note that the prior self-resonant equations in Meander Line Antenna (MLA) design included only inductive reactance (XC), neglecting the capacitive reactance (XD) equation. They address the gap by introducing new design equations, presenting a newly derived XD equation and an improved Q factor expression. The inadequacies of the existing Q factor equation, reliant on the radius of a sphere encompassing the antenna, are addressed by proposing a more fitting expression that incorporates antenna structural parameters using the ratio of reactance to resistance. The overview of existing design equations sets the stage for the introduction of these newly developed equations.
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Wideband/Dual-Band Dielectric Filtering Inverted-L Antenna With Reflective and Quasi-Reflectionless Radiation Nulls
29 December 2023 Wen Zheng, Shiyan Wang, Yin Li, Zai-Cheng Guo, Gang Zhang, Li Yang, and Roberto Gómez-García propose a class of dielectric filtering inverted-L antenna with reflective- and quasi-reflectionless-type radiation nulls to achieve wideband or dual-band operation. To this aim, a dual-function dissipative branch is exploited, which is in-parallel loaded at the feedline of the microstrip-fed dielectric inverted-L antenna. This absorptive branch, which is terminated in a grounded resistor, exhibits a quasi-complementary frequency response with regard to the one of the antenna. In this manner, it can mostly absorb the out-of-band RF-signal power not radiated by the antenna, hence creating quasi-reflectionless-type radiation nulls.
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True-Time-Delay Metasurface Assisted Broadband and Planarized Resonant Cavity Antenna
29 December 2023 Tayyab A. Khan and Alex M. H. Wong planarize a recently proposed resonant cavity antennas (RCA), which achieved a broad 3dB bandwidth of over 20% using a spherically modified ground (SMG), by replacing the SMG with a true-time-delay metasurface (TTD-MS) that mimics the both reflection phase shift and time-delay of the SMG over antenna’s entire operation bandwidth. They verify the proposed method through full-wave simulations and experimental measurements that demonstrate an impedance bandwidth (S11≤−10dB) of 32% and a 3dB-gain bandwidth of 21.3% (from 11.95 GHz to 14.8 GHz), with a peak gain of 17.5 dBi.
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Nyström-Type Technique for Electromagnetic Wave Scattering in Inhomogeneous Material, Plasma and Metamaterial Slabs
28 December 2023 John L. Tsalamengas present a simple, stable, and spectrally-accurate quasi-analytical method for studying the reflection, transmission, and radiation of EM waves in the presence of single-layer or multilayer material, plasma, or metamaterial slabs that are inhomogeneous along the normal to the slab interfaces. Our approach formulates the problem as a linear Volterra integral equation of the second kind, discretized using an entire-domain Nyström method with a high-order Gauss-type quadrature.
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A Dual-Polarized and Wideband Switchable Absorption/Transmission Frequency Selective Surface With Multispectral Functionality
25 December 2023 Huangyan Li, Youyi Feng, Minxin Zhao, Xiang Wang, Danilo Brizi, Xiaoxing Fang, Jun Hu, Boyu Sima, Zhiyuan Zong, Wen Wu and Agostino Monorchio develop a microwave absorption/transmission switchable frequency selective surface (A/T-SFSS) with enhanced multispectral functionality in the visible and infrared spectra. By controlling the flowing liquid medium (pure water in this work), efficient manipulation of two opposite states, absorption and transmission, can be achieved in the microwave frequency band with a wide switchable bandwidth. When functioning as a wideband absorber, the proposed A/T-SFSS exhibits an absorption rate over 90% from 6.50 GHz to 10.48 GHz.
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Compact Omnidirectional Circularly Polarized Antenna via Alford Loop and Wire-Patch Structure Combination
08 December 2023 Francesco Positano, Luca Santamaria, Robert Staraj and Leonardo Lizzi present a compact single-fed omnidirectional circularly polarized (OCP) antenna. The circular polarization is obtained by combining an Alford Loop (AL) and a Wire-Patch (WP) radiating structures, which are used to generate two orthogonal E-field components. The antenna exhibits a clear right-handed circular polarization (RHCP) with a dipole-like omnidirectional radiation pattern. A prototype has been realized using two FR-4 printed circuit boards (PCBs) and experimentally tested.
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The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links
08 December 2023 Francesco Capelletti, Carlo Riva, Giuseppe Roveda and Lorenzo Luini Investigate the path reduction factor (PRF), a key element of semi-empirical rain attenuation statistics prediction models, to shed some light on its value for links shorter than 1 km. PRF is here calculated from simulations underpinned by the use of the Enhanced Synthetic Storm Technique (E-SST) to take into account the rain rate spatial distribution along the path. This novel approach, in contrast with the more customary one of inferring a PRF model from measurements, offers the advantage of avoiding considering any unwanted additional attenuation not due to precipitation, but typically linked to system-induced effects.