Recent Articles
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Enhancing Transparent Circularly Polarized Antenna Performance for Automotive Applications
17 September 2024 Maryam Faizi Khajeim and Rashid Mirzavand investigate the impact of the vehicle body on the transparent circularly polarized (CP) antenna’s performance when installed on the vehicle windshield. The incorporation of an absorber layer on the vehicle floor to improve the antenna’s performance has been proposed. The study also evaluates how the placement of the antenna on the windshield affects its performance. Utilizing a transparent CP spiral slot antenna operating at 1.227 GHz and 1.575 GHz, the results reveal that the radiation performance of CP antennas on windshields significantly depends on their positioning.
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Beamforming Analysis of Dual Beam Antenna Array Using Theory of Characteristic Modes
26 August 2024 Mahrukh Khan, Talha Murad and Nicholas Lusdyk present a novel and insightful approach to beamforming a 2×2 antenna array using the theory of characteristic modes. The array comprises four rectangular patch antenna elements designed on an FR-4 substrate resonating at 2.4 GHz. The characteristic mode analysis (CMA) presented a fascinating physical insight into the surface current directions and the radiation characteristics of the array structure. The excitation of a specific characteristic mode led to the design of a dual-beam antenna array. After feed excitation, characteristic mode analysis (CMA) was employed to understand multi-beam pattern reconfigurability in the multi-port structure.
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A Study of Wideband and Compact Slot Antennas Utilizing Special Dispersive Materials
05 July 2024 Xiantao Yang, Ilkan Calisir, Lyuwei Chen, Elliot Leon Bennett, Jianliang Xiao and Yi Huang present a novel technique for enhancing the slot antenna bandwidth using special dispersive materials for the first time. The dispersive material whose relative permittivity is inversely proportional to the frequency by the power of n is selected and exploited for antenna bandwidth enhancement and size reduction. The concept and theory behind this work are explored. A slot antenna loaded with the new material is proposed and it is shown that the bandwidth of slot antennas using the material with power n=2 can be significantly improved with more than 4 times larger than the traditional case ( n=0 ).
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Ultra-Wideband Frequency-Invariant Beamforming Using a Generalized Nesting Array
05 July 2024Taeho Yu, Jin Myeong Heo, Cheolsun Park, Yong Ku Jeon and Gangil Byun propose an ultra-wideband frequency-invariant beamforming (FIB) using a generalized nesting array. To implement ultra-wideband (9:1 bandwidth ratio) FIB with a reduced number of array elements, the target frequency band is divided into subbands. The subarrays have integer multiples of inter-element spacing of half-wavelength at the maximum frequency according to the bandwidth ratio of subbands. Due to this integer multiple relationships, the array elements of the subarrays are superimposed so that the total number of array elements is reduced while maintaining FIB performance over the target frequency band. Then, the FIB weights are derived based on the desired beam pattern using the inverse Fourier transform. A Bartlett beamformer is used to generate FIB patterns of the proposed nesting array.
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A Proton Irradiated CMOS On-Chip Vivaldi Antenna for 300 GHz Band Slat Array Implementation
03 July 2024 Hans Herdian, Chun Wang, Takeshi Inoue, Atsushi Shirane and Kenichi Okada propose an end-fire on-chip Vivaldi antenna on a standard 65-nm CMOS process for the 300 GHz band operation. The Vivaldi architecture was chosen for its broadband and end-fire radiation characteristics. End-fire antenna is required for slat array topology, which enables 2 D array implementation for transceivers with circuit area above 0.5λ0×0.5λ0. The antenna length was shortened to maximize beamwidth and reduce area. Additionally, comb-shaped slots were added to suppress side lobes and back radiation caused by the short length.
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On Embedded Element Radiation Function and Beam Direction of Wide-Scanning Array Antennas
28 June 2024 Prabhat Khanal and Jian Yang presents a rigorous new analytical derivation of the theorem on the embedded element radiation function of ideally infinite planar array antennas, along with a formula for accurately calculating the main beam direction of finite-sized array antennas based on the theorem. It validates the previously established formula of the embedded element radiation function, where the amplitude is proportional to cosθ, based on the intuitive reasoning that the effective area of an element should be proportional to its projected area in the direction of interest angle θ, provided that the array antenna has no grating lobes for the full scan, no surface waves, no losses, and active impedance matched.
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A Novel Theoretical Modeling of the Received Power for Phased Array-Based Wireless Power Transfer System in the Near-Field Region
30 May 2024 Nabanita Saha, Erik Pineda Alvarez and Ifana Mahbub propose, analyze and experimentally validate a novel theoretical model to calculate the received power from individual elements of the transmitter array antenna and estimate the received power, specifically in the near-field region. The proposed WPT technology utilizes a 2.4 GHz radiative near-field (Fresnel region) power transmission scheme. The calculated results using this analysis have been verified using a complete phased array antenna-based wireless power transfer system.
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Fading in Reflective and Heavily Shadowed Industrial Environments With Large Antenna Arrays
12 April 2024 Sara Willhammar, Liesbet van der Perre and Fredrik Tufvesson perform measurements in an operating factory environment at 3.7 GHz with a co-located massive multiple-input multiple-output (MIMO) array and a unique randomly distributed array. Channel hardening can appear when the number of antennas is increased such that the variations of channel gain (small-scale fading) is decreased and it is here quantified. The cumulative distribution function (CDF) of the channel gains then becomes steeper and its tail is reduced. This CDF is modeled and the required fading margins are quantified. By deploying a distributed array, the large-scale power variations can also be reduced, further improving reliability.
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Simple and Low-Cost Shared-Aperture Antenna Module for 5G N78 and N257 Applications
22 February 2024 Danle Ma, Jiawei Zhu, Runjie Diao, Ruiping Liang, Huiming Li, Jun Huang, Hui Tang, Yue Cao and Jian-Xin Chen propose a simple and low-cost shared aperture antenna module for 5G N78 and N257 applications. This module integrates a microwave (MW) patch antenna and a millimeter wave (MMW) substrate-integrated waveguide (SIW) slot antenna. The MW part employs splits etched on the patch and shorting vias to excite TM01, TM20, and TM21 modes simultaneously and generate a wide band covering N78 band. In the MMW part, beveled SIW cavities with additional metal vias are set on the same substrate of the patch antenna and extend the bandwidth of the slot antennas covering N257 band. The shared-aperture antenna module provides high port isolations, and high and flat gains for both bands.
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Compact High Gain Wideband Circularly Polarized Non-Uniform Metasurface Antenna Through Improved Mode Coupling
01 February 2024 Komal Iqbal, Qasim Umar Khan and Zubair Ahmed present a wideband, high gain circularly polarized (CP) metasurface (MTS) based slot antenna. The designed nonuniform slots provide wider bandgap regions and extra degree of freedom in tuning to obtain wider impedance bandwidth through improved mode coupling for fixed optimum feed location along with improved 3-dB axial ratio bandwidth and gain. The extra radiation edges provided by nonuniform slots within the unit cell help in improving mode coupling thus resulting in increased performance of the designed antenna. Improved mode coupling in case of the proposed antenna is explained and verified using characteristic mode analysis (CMA).