High-Selectivity Frequency-Selective Rasorber Based on Low-Profile Bandpass Filter

A frequency-selective rasorber (FSR) with a high selectivity transmission passband and two absorption bands is proposed in this letter. The design method is introduced based on the equivalent circuit model (ECM). This structure consists of a lossy layer and a lossless layer. The lossy layer is composed of Jerusalem elements with a parallel resonance unit in center, and load with resistors on the metal branch. The lossless layer is integrated by a multilayer frequency selective surface to realize the high selectivity and wide transmission band. The surface current distributions and surface loss density were illustrated to explain the working principle. The simulated results show that the 1 dB transmission window is obtained from 7.9 to 9.0 GHz. The -10 dB absorption bands are over 3.3-7.1 GHz and 9.4-12.0 GHz. A prototype of the proposed FSR was fabricated and measured to verify our design; the measured results show a good agreement with simulated results.