Recent Articles
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A Design of Orthomode Transducer Loaded With Polarization Grid
22 January 2025 Yuying Li, Zhaoran Chen, Kaiyan Huang and Xiayuan Yao propose a design of an Orthomode Transducer (OMT) loaded with a polarization grid based on the traditional T-junction OMT structure. Additionally, a conical horn is integrated into the presented OMT. The entire system was subjected to simulation, fabrication, and measurement. In 29.8–32.2 GHz, both the simulated and tested Voltage Standing Wave Ratio (VSWR) values for the two orthogonal ports remain below 1.2, with a measured isolation of 60–75 dB. At 31 GHz, there is a good agreement between the simulated and measured far-field patterns for the main polarization, with cross polarization levels measured at less than −15 dB.
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6G RIS in Indoor Environments: Assessment of Exposure Variability in Human Users and Non-Users
16 January 2025 Silvia Gallucci, Martina Benini, Serena Fiocchi, Gabriella Tognola and Marta Parazzini assess the exposure of human users and non-users in indoor scenarios due to novel technology that will be integrated in 6G network in order to overcome the obstacles in NLOS area: Reconfigurable Intelligent Surface (RIS), here tuned in FR1-band. The exposure assessment was conducted in two simplified indoor scenarios, single room and office, where the transmission angle of the RIS were varied mimicking the RIS following the user, and the Specific Absorption Rate (whole-body and brain SAR) were calculated. Five human models from Virtual Population (ViP) were considered differing between each other for anatomical characteristics.
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A Design Method to Increase the Bandwidth of Reflectarray Antennas
16 January 2025 Christos Exadaktylos, Anastasios G. Koutinos, Constantinos L. Zekios and Stavros V. Georgakopoulos introduce a novel design methodology to redesign traditional reflectarray antennas (RAs) with bandwidths in the order of 15% and double their bandwidth without increasing their design complexity. A wideband RA unit cell (UC) is designed utilizing multiple connection points between the radiating and phase shifting structure. Notably, to properly set the desired phase shift at each UC of the RA aperture across the entire frequency band, true-time-delay (TTD) lines are connected to each element. To validate the performance of our proposed approach a traditional microstrip patch-based RA is used as an example.
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Beam Shaping by Phase-Only Waveform Encoding for Transmitting Array Antennas in Radar Applications
14 January 2025 Lior Maman, Shlomo Zach and Amir Boag propose and compare two beam broadening methods for active electronically scanned array (AESA) antennas with uniform amplitude excitation: phase tapering optimization (PTO) and a novel time-varying phase tapering (TPT). The PTO is a simple and efficient approach assuming continuous polynomial phase distribution and requiring optimization of only few parameters. The TPT is valid mainly for radar applications, taking advantage of the fact that radars typically transmit pulse trains for coherent integration. By incorporating waveform encoding and varying the array elements’ phases from pulse to pulse, the TPT achieves effective amplitude tapering, enabling precise beam shaping and the realization of any amplitude aperture illumination using phase-only control, thus providing a method of beam shaping, occasionally with a simple analytic form.
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Synthesis of Wide-Angle Scanning Arrays Through Array Power Control
13 January 2025 Pietro Rosatti, Giacomo Oliveri and Andrea Massa propose a new methodology for the synthesis of wide-angle scanning arrays.It is based on the formulation of the array design problem as a multi-objective one where, for each scan angle, both the radiated power density in the scan direction and the total reflected power are accounted for. A set of numerical results from full-wave simulated examples - dealing with different radiators, arrangements, frequencies, and number of elements - is reported to show the features of the proposed approach as well as to assess its potentialities. A widening of the field-of-view percentage of up to 22% with respect to standard scanning methods is demonstrated.
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Near-Ground Propagation Channel Modeling and Analysis in Underground Mining Environment at 2.4 GHz
08 January 2025 Isam Eddine Lamri, Mourad Nedil, Mohamed Nasr Eddine Temmar and Nahi Kandil present a detailed measurement and performance analysis of near-ground propagation channels in an underground mine for both Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) scenarios. The analysis is derived from channel measurements conducted at a frequency of 2.4 GHz with a bandwidth of 200 MHz, utilizing four different combinations of transmitter-receiver (Tx-Rx) antenna heights ranging from 10 cm to 120 cm. Key channel characteristics such as large-scale path loss, time dispersion, and coherence bandwidth are reported and evaluated. The study suggests that a multi-slope (four-slope) path loss model is more effective in predicting path loss across various propagation segments in the mining environment.
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Optimal Frequencies for Wireless Power Transfer Through Biological Tissues
06 January 2025Nam Ha-Van, Sergei A. Tretyakov and Constantin R. Simovski present a comparative theoretical study of a basic wireless power transfer (WPT) system for two cases: when both transmitting and receiving loops are inside a biological tissue (human body) and when the transmitting loop is outside while the received loop is inside. The study aims to find and compare optimal frequency ranges of WPT, distinguishing the regimes of maximal efficiency and maximal transferred power for both of these cases. It is found that the impact of the interface results in a significant increase in the frequencies that are optimal for the maximum power transfer efficiency: from dozens of MHz for a WPT system entirely located in the medium to the GHz range for a WPT system with the transmitting antenna in free space.
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Digitally Controlled Beam-Steerable Printed Dipole Antenna
3 January 2025 Rajesh Shukla, Sandeep Kumar Yadav and Soumava Mukherjee propose a digitally controlled beam steerable printed dipole antenna operating in ISM band using PIN diodes switching mechanism. The proposed antenna provides effective solution of beam steering by establishing adequate coverage in elevation plane using a single dipole element. The beam steering of antenna has been digitally controlled by varying the effective length of one dipole arm by switching the PIN diodes integrated on it. For effective digitally controlled beam steering, the DC biasing voltage applied for switching PIN diodes is regulated by Pulse Width Modulation (PWM) signal generated from STM32F407VG microcontroller through RC filter.
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A Compact Shared-Aperture Antenna With 2-Transmit and 2-Receive Highly-Isolated Ports for Full-Duplex MIMO Systems
01 January 2025 Junhui Rao, Zhaoyang Ming, Jichen Zhang, Zan Li, Chi-Yuk Chiu and Ross Murch propose a compact multiple-input multiple-output (MIMO) In-band full-duplex (IBFD) antenna featuring two co-polarized transmit (Tx) ports and two co-polarized receive (Rx) ports that is suitable for use in mobile devices. The design is one of the first to include MIMO into IBFD antennas. The fabricated and measured proposed antenna exhibits over 32 dB self-interference (SI) isolation between Tx and Rx ports and less than −18.2 dB mutual-coupling (MC) within Tx and Rx pairs. All radiation patterns are in the broadside direction and it operates in the 2.5 GHz frequency band.
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Pattern Compensation for Faulty Phased Array Antenna Based on Deep-Learning Technique
23 December 2024 Shu-Min Tsai, Ming-Tien Wu, Yu-Han Chen, Hong-Wei Yan and Ming-Lin Chuang propose an approach to compensate for pattern distortion in a phased array antenna caused by antenna element failures. The proposed approach utilizes a deep-learning network explicitly trained for a phased array antenna with damaged elements to generate the necessary excitation, producing a new pattern closely resembling the intact phased array antenna. Compared to alternative methods that focus on reducing side-lobe level, this compensation approach offers the advantages of rapid response and minimal computational overhead for the re-synthesis of the desired pattern that is close to the original pattern. This approach makes it particularly suitable for scenarios involving faulty phased array antennas, such as those on satellites or mountain-top antenna towers, where replacement or repair is not readily feasible in a short timeframe.
