Design of high-absorption electromagnetic absorber through synergistic integration of frequency selective surfaces and 3D metastructures for broadband and wide-angle applications

A wideband three-dimensional (3D) electromagnetic absorber with a large incidence angle is designed and experimentally investigated using a design methodology that integrates resistive frequency selective surfaces (RFSS) with three-dimensional metastructures (3D MS). The RFSS acts as a strong absorption layer, while dual 3D MSs (3D MS-I/II) with low loss characteristics synergistically broaden absorption bandwidth. Multi-interface exploitation optimizes angular stability, featuring resistive patch integration in 3D MS-II for compensation absorption under TE polarization and strategically positioned vertical metal patches in 3D MS-I extending the propagation distance of electromagnetic waves in 3D MS-I under TM polarization. Benefiting from the hybrid absorbing mechanism, the proposed absorbing material demonstrates over 90% absorptivity from 6.3 to 27.2 GHz with angular stability below 60°, covering full X/Ku bands (−20 dB bandwidth). Notably, 80% wideband absorption persists even at 70° oblique incidence.