Wideband RCS-Reduced High-Gain Fabry–Perot Antenna Based on Chessboard Frequency Selective Rasorber

This letter proposes a high-gain in-band and out-of band low radar cross section (RCS) Fabry-Perot (FP) antenna based on a chessboard frequency selective rasorber (CFSR). The frequency selective rasorber (FSR) unit exhibits frequency selective absorption characteristics through the co-design of transmissive impedance surface and frequency selective surface (FSS). Regarding in-band and out-of-band low RCS, a CFSR structure composed of FSR1 and FSR2 chessboard arrangement is introduced as the partially reflecting surface (PRS) of the FP antenna. This configuration not only enables out-of-band RCS reduction through the out-of-band selective absorption property of CFSR, but also realizes in-band RCS reduction through redirection of reflected waves and destructive interference caused by a 180° ± 30° phase difference of reflected and retransmitted waves. The FP resonant cavity structure enhances the antenna's radiation gain. Measurement results demonstrated that the FP antenna attains a maximum gain of 13.1 dBi at 5.8 GHz, with a 10-dB impedance bandwidth of 5.35-6.07 GHz (12.6%), and a peak RCS reduction of 22.6 dB, alongside an effective RCS reduction bandwidth spanning 2-12 GHz (142.8%).