Low radar cross section checkerboard metasurface with a transmission window

In this paper, we propose the design of a hybrid surface with a low radar cross section (RCS) at lower frequencies and a transmission window at higher frequencies. The hybrid surface comprises two parts: a frequency selective surface (FSS) on the bottom and a checkerboard metasurface on the top. The FSS exhibits low-stop and high-pass properties, which reflects waves at lower frequencies and allows transmission of waves at higher frequencies. The checkerboard metasurface, with a reflective substrate, can reduce RCS at lower frequencies by means of scattering cancellation. Due to the low-stop property of the FSS, the hybrid surface can achieve broadband RCS reduction at low frequencies since the FSS acts as the reflective substrate. Simultaneously, the transmission window at higher frequencies of the FSS can be kept. Simulation results show that the RCS can be reduced by more than 10 dB in 4.1-7.7 GHz and the insertion loss in the transmission window is lower than 1.0 dB in 11.3-13.3 GHz. A prototype was fabricated and measured. The experimental results agree well with the simulation results. This work provides an effective alternative to the design of functional devices such as stealthy radomes, etc.