PIER M | PIER Journals

2025-03-25

PIER M

Vol. 133, 21-31, 2025

download: 31

Dual-Circularly Polarized Miniaturized Metasurface-Loaded Rhombic Loop Broadband Antenna for Sub-6 GHz 5G RFEH Applications

Sanjay Kumar Sharma, Taimoor Khan and Hitendra Singh

In this paper, a dual-circularly polarized (DCP), metasurface-loaded broadband antenna is designed to operate across frequencies covering the Sub-6 GHz 5G band for RF energy harvesting (RFEH) applications. The DCP antenna can collect RF energy both left-hand circularly polarized (LHCP) and right-hand circularly polarized (RHCP) waves by the same antenna. In this view, the antenna structure features two crossed metallic strips enclosed within symmetrically loaded metallic rhombic loops. Unequal strip widths in the rhombic loops enhance gain and improve impedance matching. A partial ground plane on the bottom layer fine-tunes the operating frequency, while the metasurface boosts antenna gain. A prototype with optimized dimensions was fabricated, and the results, both experimental and simulated, demonstrated excellent agreement.

Dual-circularly Polarized Miniaturized Metasurface-loaded Rhombic Loop Broadband Antenna for Sub-6 GHz 5G RFEH Applications

2025-03-20

PIER M

Vol. 133, 11-19, 2025

doi:10.2528/PIERM25021503

download: 44

Optimizing Radar Stealth by Near-Field Diagnostics of Aircraft Engine Absorbent Material Coating

Yulang Li, Hongwei Deng, Linyuan Dou and Zeyong Wei

This study introduces an approach for applying radar-absorbent material (RAM) coatings on aircraft engines to reduce the monostatic radar cross-section (mono RCS), leveraging near-field diagnostic analysis to guide the process. The primary goal is to improve the mono RCS stealth performance within the engine's intricate cavity structure. The finite-difference time-domain (FDTD) method is employed to accurately compute near-field distributions within the cavity, accounting for the complex interactions of electromagnetic wave propagation and scattering. This analysis method identifies critical hotspots within the engine cavity that significantly impact the RCS. An RAM coating scheme is then designed to target these ``hot spots'', resulting in substantial RCS reduction of the engine. The findings highlight the accuracy and effectiveness of this methodology, offering valuable contributions to the advancement of stealth technologies for next-generation aircraft engines.

Optimizing Radar Stealth by Near-field Diagnostics of Aircraft Engine Absorbent Material Coating

2025-03-17

PIER M

Vol. 133, 1-9, 2025

doi:10.2528/PIERM24122006

download: 56

A Frequency Selective Rasorber with Ultra-Wideband Switchable Transmission/Reflection and Two-Sided Absorption

Liangzhen Lin, Jianqiong Zhang, Liangzhu Li, Xiang-Qiang Li and Qingfeng Wang

A novel switchable frequency selective rasorber (FSR), featuring dual wideband absorption bands and an ultra-wide passband that can be switched to a reflective band, is proposed in this work. This design incorporates a lossy layer and a three-layer reconfigurable frequency selective surface (FSS). An ultra-wideband transmission can be achieved through the lossy layer by means of circular spiral resonators. The switchable function is utilized by a reconfigurable FSS with PIN diodes. Simulation results confirm the FSR's broad absorption from 1.44 to 2.39 GHz (49.6%) and from 5.45 to 6.64 GHz (19.7%). It also achieves an extensive passband with a 1-dB bandwidth of 47.78% (3.17~5.16 GHz) in the absorption-transmission-absorption (A-T-A) mode, which is the widest transmission band in existing designs. The passband is converted into a reflection band in the absorption-reflection-absorption (A-R-A) mode, showcasing the FSR's switchable characteristics. To validate these simulation outcomes, a prototype measuring 300 x 300 mm is constructed and measured.