Absorptive/Transmissive Frequency Selective Surface With Wide Absorption Band

An absorptive/transmissive frequency selective surface (ATFSS) with absorption bands at both sides of a passband is presented. Equivalent circuits of the ATFSS that consists of a lossy frequency selective surface (FSS) and a lossless FSS were modeled. To improve the rejection at an undesired band, a transmission zero was introduced and controlled by loading the lossless FSS with four-legged loaded slots. The parasitic passband was suppressed when the cross structure in the lossless FSS was loaded with resistance. In order to expand the absorption band, loaded dipoles were utilized for the lossy FSS design. An ATFSS with wide absorption bands was realized after three ATFSSs with different performances were investigated. The proposed ATFSS was fabricated and measured. The measurement results showed that a passband at around 5 GHz with a minimum insertion loss of 0.92 dB was obtained. Within an ultrawide band from 2.8 to 11.4 GHz with vertical bar S-11 vertical bar < -10 dB, the absorption rates of higher than 80% were obtained at a lower absorption band, from 2.7 to 3.8 GHz, and at a higher absorption band, from 6.2 to 11.7 GHz. Our results showed good agreements between the measurements and simulations.