Broadband-Transmissive, Frequency-Selective Rasorber Design Using Characteristic Mode Analysis

This article designs a frequency-selective rasorber (FSR) with a broadband transmission window. It is synthesized by a broadband absorber and a frequency-selective surface (FSS). The resistive layer achieves broadband absorption by introducing a tortuous Jerusalem cross load with lumped resistors, and the lossless FSS adopts a three-layer metal structure to realize the broadband transmission window. The absorption mechanism of the resistive layer is analyzed using the theory of characteristic mode. The position of the resistor is determined according to the analysis of mode current distribution and parameter optimization. Prototypes of the structure were fabricated and measured, and the simulation results show that the 1 dB transmission window and the absorption band with vertical bar S11 vertical bar < -1 dB are 36.4% and 97%, respectively. Therefore, the designed FSR has potential application prospects in electromagnetic stealth technology and radar cross-section reduction.