Lossy Frequency‐Selective Surface Metamaterials Based on Silicon Slice with Broadband Microwave Absorption at Elevated Temperature

Abstract

A broadband metamaterial absorber (MA) with high‐temperature resistance is designed and fabricated using a regular octagonal ring‐cross structure as a frequency‐selective surface (FSS). A high‐temperature conductive paste and SiO2 are used as the FSS raw materials and middle layer, respectively. Simulation and experimental results show that the absorber reaches a reflection loss below −5 dB at the 5.17–18 GHz range with normal incidence at room temperature. The measured values are in good agreement with the simulation results. At 800 °C, the absorption bandwidth expands to 13.3 GHz (4.72–18 GHz). The equivalent impedance of the absorber is obtained using an inversion method to qualitatively explain its working mechanism. The electric energy density, magnetic energy density, and surface current at the resonance frequency provide an intuitive understanding of the power loss of the structure. Comprehensive analysis illustrates that the main absorption mechanisms of the high‐temperature broadband MA (HBMA) are ohmic and resonance losses.