Recent Articles
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Improving DOA Estimation via an Optimal Deep Residual Neural Network Classifier on Uniform Linear Arrays
05 February 2024 Haya Al Kassir, Nikolaos V. Kantartzis, Pavlos I. Lazaridis, Panagiotis Sarigiannidis, Sotirios K. Goudos, Christos G. Christodoulou and Zaharias D. Zaharis improve and evaluate the effectiveness of the neural network (NN) architecture in the domain of estimation of direction of arrival (DOA), with an emphasis on a multi-class classification task with grid resolutions of 0.25 and 0.1. Specifically, a comprehensive assessment is performed to determine the competence of a residual NN (ResNet) in predicting the angle of arrival (AOA) of intercepted signals. Such signals are received by a 16-element uniform linear array and are subjected to real-world noise conditions.
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Beam Steering Performance of an X-Band Offset Parabolic Cylindrical Reflector Fed by Triple-Mode Horn Integrated With Risley Prism and Phase Correcting Dielectric Lens
05 February 2024 Kaushik Debbarma, Satish Kumar Sharma, Jia-Chi Samuel Chieh and Nhat Truong present a broadband 1-D high-gain beam steering solution to steer sum and difference patterns for tracking the optimum common scatter volume of troposcatter links at X -band. The novel steering arrangement consists of a D=70 cm offset parabolic cylindrical (OPC) reflector fed by a triple-mode circular waveguide (TM-CW) horn antenna integrated with a two-element dielectric wedge-based Risley prism and a parabolic phase correcting dielectric lens (PCDL). The proposed hybrid beam steering reflector-feed obviates the need for complex 3-axes based gimbals to mechanically steer the conventional reflector-feed assembly.
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The Effective Number of Degrees of Freedom of the Far-Fields Radiated by Rectangular Current Sheets
30 January 2024 Ting Zang and Gaobiao Xiao evaluate numerically the number of degrees of freedom (NDF) of the electromagnetic far-fields generated by current sheets under certain noise level in the environment by directly sampling on the constellation of the propagation modes in free space. The electric fields in the far region are efficiently calculated by using the far-field approximation, and the effective numbers of degrees of freedom (ENDFs) are obtained through singular value decomposition (SVD) incorporating noises. The results show that ENDF is proportional to the area of the current sheets.
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A Low-Profile Broadband Filtering Dielectric Resonator Antenna Based on SISL With the Improvement of Suppression Level
26 January 2024 Ningning Yan, Cong Wang, Yu Luo and Kaixue Ma present a substrate integrated suspended line (SISL) based broadband filtering dielectric resonator antenna (DRA) with the improvement of suppression level to achieve a low-profile, wide-bandwidth, and highly selective design. The dielectric resonator is cylindrical and fed from the bottom by a microstrip-coupled slot. The dual head structure with the designed open stub can provide two radiation nulls on both sides of the passband for the filtering function and can excite three resonant modes (HEM 11δ, HEM 11δ, and TE131 mode) at different resonant frequencies to enlarge the impedance bandwidth of the proposed antenna.
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Connected Antenna Arrays With Beamsteering Capability for On-Package Millimetre-Wave Applications
25 January 2024 Md Rasheduzzaman Al-Amin, Reza Shamsaee Malfajani, Elham Baladi and Mohammad S. Sharawi design, fabricate and measure on-package, beamsteerable, slot-based connected antenna arrays (CAA), namely a single slot connected antenna array (SSCAA) and a double slot connected antenna array (DSCAA) for millimeter-wave (mm-wave) applications. Both structures are designed in a multi-layer stack-up fashion considering the package environment. The proposed SSCAA and DSCAA show 12.3% (centered at 27.55 GHz) and 16.5% (centered at 30.2 GHz) of measured bandwidths (−10 dB return loss) in their respective operating frequency bands. The measured realized gains of the SSCAA and DSCAA are 9.89 dBi and 12.5 dBi at broadside, demonstrating efficiencies of 89% and 78% respectively.
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Mm-Wave Building Penetration Losses: A Measurement-Based Critical Analysis
18 January 2024 Silvi Kodra, Marina Barbiroli, Enrico Maria Vitucci, Franco Fuschini and Vittorio Degli-Esposti carry out a measurement campaign at 27 and 38 GHz to investigate the coverage and interference assessment issues of mm-wave radio links in in-building applications, and in particular, analyse the outdoor-to-indoor and through-floor attenuation. It is observed that in-building losses heavily depend on the building type, and that modern construction techniques make through-floor penetration almost impossible.
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Compact Dielectric Resonator Antenna With Improved Bandwidth via Loading of Metal Ring
16 January 2024 Hui Gu and Lei Ge propose a novel dielectric resonator antenna (DRA) characterized by a compact size and wide bandwidth. The achievement of wideband performance involves the introduction of a metallic ring structure inside the dielectric resonator, ensuring that the antenna’s volume remains compact. Fundamental and higher-order modes, TM01δ, TM021+δ of the cylinder DRA are first investigated by using E-field distribution analysis, and it is found that these two modes are hard to resonate in proximity to each other. Therefore, a thin metal ring, acting as a perturbation structure is inserted into the DR to perturb the E-field of the higher-order mode and reduce its resonant frequency.
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Aperture Efficiency of Non-Uniform Antenna Arrays With Controlled Sidelobe Level
15 January 2024 Ahmed Alieldin and Yi Huang presents a comprehensive study and proposes accurate mathematical modelling of the aperture efficiency of an antenna array which is divided into two components: power-loss efficiency (which dominates total aperture efficiency) and power-distribution efficiency to gain a better understanding. The paper also shows how the sidelobe level of an antenna array is linked to these efficiencies and how they can be improved. It is proved that the aperture efficiency exponentially decays when lowering the sidelobe level. However, it converges to a certain value when the sidelobes vanish.
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Calderón Strategies for the Convolution Quadrature Time-Domain Electric Field Integral Equation
15 January 2024 Pierrick Cordel, Alexandre Dély, Adrien Merlini and Francesco P. Andriulli introduce new integral formulations based on the convolution quadrature method for the time-domain modeling of perfectly electrically conducting scatterers that overcome some of the most critical issues of the standard schemes based on the electric field integral equation (EFIE). The standard time-domain EFIE-based approaches typically yield matrices that become increasingly ill-conditioned as the time-step or the mesh discretization density increase and suffer from the well-known DC instability. This work presents solutions to these issues that are based both on new Calderón strategies and quasi-Helmholtz projectors regularizations.
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An Integrated DRA-Based Large Frequency Ratio Antenna System Consisting of a MM-Wave Array and a MIMO Antenna for 5G Applications
03 January 2024 Awab Muhammad, Muhammad U. Khan, Reza Shamsaee Malfajani, Mohammad S. Sharawi and Moath Alathbah present a large frequency ratio antenna that covers the widely separated 5G bands. The proposed antenna consists of a 2-element rectangular DRA (rDRA)-based MIMO antenna for the sub-6 GHz band, with an embedded 1×4 cylindrical DRA (cDRA) array covering the mmW band. The rDRAs are fabricated through a cost and time-efficient 3D printing process, whereas small dimensions of cDRAs are precisely machined through a CNC. The proposed antenna has a measured impedance bandwidth of 31.63% at 4.9 GHz and 21.5% at 28 GHz. The antenna has a peak gain of 6.6 dBi at the sub-6 GHz and 12 dBi at the mmW bands.