Design of frequency selective rasorber with high in-band transmission and wideband absorption properties

A low-frequency transmissive frequency selective rasorber (FSR) with high in-band transmission and wideband absorption characteristics is proposed and experimentally demonstrated. It comprises the top resistive sheet and the bottom bandpass FSS. For resistive sheet, the tiny strip-type parallel LC resonator composed of square spiral inductor and its two-sided capacitors is inserted between the resistor-loaded crosses to achieve lower insertion loss (IL) by cutting off the lossy path. The bandpass FSS with high selectivity consists of Jerusalem cross slot array and capacitive metallic patches. An IL of 0.3 dB is obtained at 3.55 GHz, and the 10-dB-absorption band is 5.4–13.2 GHz.