Polarization-Insensitive Dual-Band Frequency Selective Rasorber based on Concentric SRRs

In this paper, a dual-band frequency selective rasorber (FSR) has been presented based on concentric split ring resonator geometry. The proposed design comprises a top lossy layer and a bottom lossless layer separated by a quarter-wavelength thick air spacer. Theoretical analysis of the structure exhibits an overall absorption band ranging from 2.2 to 9.0 GHz (with a fractional bandwidth of 121.43%), whereas two discrete passbands appear at 3.54 and 9.0 GHz having insertion loss of 0.7 and 1 dB, respectively. In addition, the proposed topology is polarization-insensitive and angularly stable unlike the existing multi-band FSR geometries. The physical insights behind the absorption and transmission mechanism have also been explained by analyzing the surface current distribution of the structure.