Dual-Polarized A-T-A Frequency Selective Rasorber Based on Cross-Dipole and Interdigital Resonator

This paper presents a dual-polarized frequency selective rasorber (FSR) that features two absorption bands on both sides of a passband. The structure of the proposed FSR consists of a resistive absorber frequency-selective surface (FSS), a passband FSS, and an air gap between the layers. Interdigital resonators are implemented to guarantee parallel resonance in the resistive layer, whose unit cell element is a resistor-loaded cross-dipole. The FSR exhibits a passband of high selectivity around 4.78 GHz with a minimum insertion loss of 0.77 dB and provides an operating bandwidth from 2.32 to $8.33 \mathrm{GHz}\left(\left|S_{11}\right|\lt -10 \mathrm{~dB}\right)$, under normal incidence. The proposed rasorber is capable of reducing the radar cross section of communication systems operating in the C-band, by reducing out-of-passband reflections in other directions, giving them stealth characteristics. The FSR prototype was fabricated with a low-cost FR-4 substrate in both layers, and measured for validation.