Bandpass Frequency-Selective Rasorber With Wide Transmission Band and High Selectivity Based on Multiorder Resonance

Previously, cascaded frequency-selective rasorbers (FSRs) with low structural complexity only obtained single-order passbands, which always leads to wide transition band, where energy leakage happens to seriously damage the low out-of-band scattering characteristics. In this article, a novel method for enabling high-selectivity cascaded FSRs with wide multiorder passband is proposed to solve this problem. The multiorder transmission resonance fusion technology of the lossy layer is broken through from the perspective of analyzing resistance limitation on the transmission performance. Combined with a triple-layer bandpass frequency-selective surface (FSS), a 2-D planar cascaded FSR with a wide double-order transmission band is realized. Its -1-dB transmission band is 7.66-11.76 GHz, and bandwidth (BW) reaches 42.2%. The defined overall FSR selectivity coefficient FSR SF-1 dB80% is less than 1.45, which reflects great selectivity. A prototype is fabricated and measured, and reasonable agreement between the simulation and experimental results validates our method.