Band‐notched frequency‐selective absorber with linear polarization rotation function

Abstract

This article presents a novel band‐notched frequency‐selective absorber (BFSA) with linear polarization rotation function in‐band and absorption out‐of‐band. When used as an antenna reflector, the BFSA can not only reduce RCS outside of the antenna's working band, but also reduce co‐polarized RCS within the working band and improve cross‐polarized reflection. The BFSA realizes −0.41 dB linear polarization‐rotating reflection at 4.5 GHz. In the upper and lower bands, the BFSA realizes a broad absorption function from 2.2 GHz to 4.1 GHz and 5.03 GHz to 6.5 GHz. The fractional bandwidth of linear co‐polarization reflection is 98.8% with 10 dB reflection reduction. The experimental measurements are conducted to validate the polarization conversion of the band‐notched absorbers, and good agreement between theory and measurement results is observed.