Low-frequency broadband multilayer microwave metamaterial absorber based on resistive frequency selective surfaces

Herein, a low-frequency broadband multilayer metamaterial absorber (MMA) based on resistive frequency selective surfaces (RFSSs) is proposed, which consists of a three-layer RFSS, three-layer polymethacrylimide (PMI) foam substrates, and a copper film. The proposed absorber has the advantages of ultra-broadband absorption with absorptivity more than 90% ranging from 1.91 to 20.78 GHz, which covers the entire S, C, X, and Ku bands with the thickness of 0.102λL (where λL corresponds to the wavelength of the lowest operating frequency). The absorption performance can keep good stability in a wide angular range for both TE and TM modes. Moreover, a prototype of the proposed MMA is fabricated and experimentally measured to demonstrate its excellent performance. The experimental results show excellent consistency with numerical simulations.