Novel Frequency-Selective Rasorber with Ultrawide Absorption Bandwidth Covering Both the X- and Ku-Bands

Abstract

A novel dual-polarized transmissive/absorptive frequency-selective rasorber (FSR) with an ultrawide absorption spectrum covering both the X- and Ku-bands is proposed in this paper. The FSR is constructed from a bottom lossless transmission layer and a top lossy absorption layer, in which a resistor-loaded incurved square loop strip line structure is utilized to obtain an ultrawide absorption band. To quantitatively analyze its operation principle, an accurate equivalent circuit model of the proposed FSR was developed. A 2D prototype was designed, assembled, fabricated, and measured. The FSR exhibits an absorption band that ranges from 8.1 to 19.1 GHz (81%) under normal incidence, whereas the passband insertion loss at 4.5 GHz is less than 0.45 dB. The total thickness of the FSR is only 5.1 mm, which keeps low profile characteristics. The simulation agrees well with the measured results.