Dual-band composite wideband absorbing material for broadband antenna in-band radar cross section reduction

Abstract

A composite wideband absorbing material (WAM) covering dual bands is designed, to reduce the in-band radar cross section (RCS) for broadband antenna in this paper. The upper layer is a traditional absorber while the lower one is a dual-band frequency selective surface (FSS), which is formed by a square ring and an improved Jerusalem cross structure. The absorbing band has been broadened to 112% compared with the magnetic sheet without FSS. Over C and X bands, the absorption rate is over 90%. By using the FSS-based WAM as the ground plane of a Vivaldi antenna, substantial RCS reduction is obtained from 2–18 GHz. Moreover, the RCS is reduced remarkably over −80◦ –80◦ incident angles except for minority angles, with the radiation performance preserved at the same time. The experimental results are in good agreement with the simulated ones.