A Dual-polarized Dual-transmission Band Frequency Selective Rasorber

In this paper, a polarization-insensitive and compact frequency selective rasorber (FSR) with two independent transmission windows and three absorption bands is presented. The proposed FSR is a two-layer structure, whose upper layer is a dual bandpass filter and the bottom layer is a lossy absorber, separated by an air spacer. The bottom lossy absorber is constructed by four folded rings loaded with four resistances and four capacitances, which realize a transmission response with two passbands and three lossy bands. As to the upper lossless filter, a double four-legged slot is etched on a square patch, which implements the same two transmission bands as the bottom layer. The two transmission bands of the FSR are at 5.3 GHz and 7.6 GHz with low insertion loss of 0.068 and 0.119, respectively. Three broad absorption bands whose absorptivity is greater than 80% in the 2.96-3.96 GHz, 6.14-6.94 GHz and 9.37-11.58GHz are realized. The polarization insensitivity is commendable, and the angular stability of TE and TM polarizations could up to 30° are achieved by the symmetric and compact structure.