Multilayer broadband metamaterial for microwave absorption based on resistive frequency selective surfaces

Achieving broadband electromagnetic wave absorption utilizating the multilayer Frequency Selective Surfaces (FSS) constitutes an effective strategy for designing ultra-thin electromagnetic protection devices. In this study, we propose a thin, broadband, and polarization-insensitive multilayer absorber. The structure encompasses two layers of FSS, a layer of polymethacrylimide (PMI) foam substrate, two additional dielectric layers of quartz glass, and a metallic ground plane. By synergistically optimizing the material parameters and the geometric configuration of the metasurface, the resultant metamaterial demonstrates absorption rates exceeding 90 % within the frequency range of 3.1–18 GHz, which spans the entire C, X, and Ku bands. Experimental results corroborate the exceptional absorption performance of the material, exhibiting good agreement with simulation outcomes. Notably, the absorber exhibits remarkable stability under oblique incidence, maintaining absorption rates above 80 % for both TE and TM polarized waves across incident angles ranging from 0° to 45° within the aforementioned frequency range. A comprehensive analysis of the polarization-insensitive broadband absorption mechanism is conducted, offering pivotal insights for the design of ultra-thin electromagnetic protection devices.