RCS Reduction of Antenna Array Using Wideband Polarization-Insensitive A-T-A Rasorber

Abstract

This letter presents a low-profile, wideband, polarization-insensitive frequency selective rasorber (FSR) designed to reduce the radar cross section (RCS) of high-gain planar antenna arrays. The proposed structure consists of a lumped resistor-based lossy top layer and a lossless bottom layer, separated by an air gap. It achieves high absorptivity (> 90%) across 3.8–7.85 GHz and 9.67–13.4 GHz, while maintaining an in-band transmission at 8.5 GHz with an insertion loss of 0.9 dB. The fourfold symmetric and compact topology ensures polarization insensitivity and angular stability up to 50° incidence. The FSR is integrated with a planar microstrip patch antenna array, effectively reducing its out-of-band RCS under X-polarization and both in-band and out-of-band RCS under Y-polarization, without affecting in-band transmission. Both the standalone FSR and the integrated antenna system have been fabricated and measured, demonstrating up to 10 dB RCS reduction over a 111% fractional bandwidth under normal incidence. © 2025 Wiley Periodicals LLC.