Highly Selective Dual-Band Frequency-Selective Rasorber with Second-Order Resonance

A dual-band frequency-selective rasorber (FSR) with highly selective passband based on second-order response is proposed in this paper. The structure is composed of a lossy layer and two lossless layers. The lossy layer is formed by dual-passband resonators to realize dual transmission performance. The lossless layer is cascaded by a two-layer square slot FSS, which realizes second -order band-pass response. The simulation shows that the transmission bands are located around 7 and 10.5 GHz, respectively. The reflection bandwidth below -10 dB covers 3.68-9.9 GHz and 10.12-11.09 GHz. Additionally, the proposed FSR shows the stable transmission and absorption performance for both TE and TM polarizations. It is worth mentioning that the dual-polarized dual-band FSR with second-order response is proposed for the first time, which improves the passband selectivity of dual-band FSR.