Design of ultra-broadband circuit analog absorbers based on resistor-loaded frequency selective surfaces

This work introduces two compact, broadband microwave metasurface absorbers based on resistor loaded frequency selective surfaces (FSS). By integrating tailored resistive and geometric elements, the designs simultaneously achieve lightweight construction, wide absorption bandwidths, and high efficiency—ideal for stealth, electromagnetic interference (EMI) suppression, and radar cross section (RCS) reduction. The absorption mechanism is elucidated through detailed electric and magnetic field analyses, revealing that the periodic cross strip and square loop FSSs generate multiple coupled resonances whose superposition yields broadband performance. Simulations confirm that a double layer cross strip design attains reflectivity below −10 dB (absorption > 90%) from 3 to 14.65 GHz, corresponding to a 132% fractional bandwidth. A hybrid single layer design combining cross strip and square loop FSSs achieves −10 dB reflectivity from 2.5 to 9.92 GHz (120% bandwidth). The proposed approach establishes an efficient pathway for designing ultrathin, broadband microwave absorbers with reduced component count and scalable manufacturability.