A Low-RCS, High-Gain and Polarization-Insensitive FP Antenna Combing Frequency Selective Rasorber and Metasurface

A novel method to engineer high-gain and polarization-insensitive Fabry-Perot (FP) antenna with low scattering is presented by combining a polarization-insensitive broadband frequency selective rasorber with partially reflective surface (FSRP) and a reflective metasurface. The FSRP element consists of an upper indium tin oxide layer printed on polyethylene glycol terephthalate substrate, a metallic loop, and a metallic patch in the middle and bottom layer, respectively, which is designed to absorb most of out-of-band incidence while achieving in-band reflection. The bottom metallic patch is a partially reflected surface which is utilized to construct an FP resonant cavity with the reflective metasurface to ensure in-band radiation. The excellent performance of proposed FP antenna is demonstrated by simulations and measurements, revealing that the antenna exhibits an in-band peak measured gain of 21.8 dBiC at 12 GHz. Besides, a significant out-of-band scattering reduction is achieved within 9.9-11.3 GHz and 13.3-20 GHz under normal detection. Our paradigm setups a new avenue for low radar cross section of a high-gain antenna, promising great potential in practical applications.