Frequency selective rasorber with broadband absorption and high selectivity based on multilayer graphene-metal hybrid structures

Abstract

In this paper, a highly integrated frequency selective rasorber (FSR) with both broadband absorption and high selectivity is designed. The proposed FSR is composed of three lossy layers and a bandpass frequency selective surface (FSS). The three lossy layers are designed based on graphene-metal hybrid structures to achieve two wide absorption bands of 1.52-7.5 GHz (132%) and 12.4-18 GHz (36.8%) without the requirement for additional lumped elements, thereby increasing the integration and design flexibility for the absorber. Meanwhile, the application of a third-order bandpass FSS and the introduction of two transmission zeros located at 8.5 GHz and 17 GHz on both sides of the passband effectively enhance the frequency selectivity characteristics of the proposed FSR, resulting in a transmission band with an insertion loss less than 1.5 dB from 8.72 GHz to 11.22 GHz (25%). Broadband absorption, wideband transmission and high selectivity properties are achieved by effectively cascading the above layers. The operating principle of the proposed absorber is analyzed through the circuit analog absorber (CAA) theory. A 26*26 scale prototype is fabricated and measured for verification. The superior performance and integrated layout make the proposed FSR highly responsive to the stealth needs of modern communication platforms.