Polarization-insensitive frequency selective rasorber with higher transmission band using modified double cross slot based bandpass layer

Abstract

In this study, a frequency selective rasorber (FSR) is proposed where a transmission band at a higher frequency is achieved besides the lower broadband absorption. The FSR is designed by combining the individual designs of broadband absorber and bandpass frequency selective surface (FSS). The broadband absorption is achieved by placing the resistive and ground layer at a distance of around λ/4 at center frequency. The unit cell of bandpass FSS is designed by etching a double cross slot. The performance parameters at the transmission band are improved by a modified double cross slot, wherein a quarter of the slot is replicated on each corner of the unit cell. The bandpass FSS replaces the ground plane of broadband absorber, in the design of proposed FSR. The proposed FSR is a polarization-independent structure exhibiting a broadband absorption from 3.1-8.7 GHz (94.91%) along with a transmission band at 11.4 GHz. The working principle of proposed FSR is illustrated by an equivalent circuit model. A range for higher transmission frequency is determined for the proposed FSR, by studying the effects of bandpass FSS parameters on the transmission performance. A prototype of the proposed FSR is fabricated, and the results are experimentally verified. © 2021 Wiley Periodicals LLC.