An ultra-wideband 2-bit coding metasurface using Pancharatnam-Berry phase for radar cross-section reduction

An ultra-wideband 2-bit coding metasurface is designed for radar cross-section (RCS) reduction. The design process is presented in detail, in which a polarization conversion metasurface (PCM) is first proposed. The proposed PCM can realize ultra-wideband circular polarization (CP) maintaining reflection. Moreover, Pancharatnam-Berry (PB) phase will be generated in the co-polarized reflection coefficient by rotating the metallic patches in its unit cells. Thus, based on the PCM, the four coding elements of a 2-bit coding metasurface are constructed using PB phase, and an ultra-wideband PB 2-bit coding metasurface is proposed according to an appropriate coding sequence. The simulated and experimental results show that the coding metasurface has obvious advantages of wideband and polarization-insensitivity. Compared to a metallic plate of the same size, it can achieve more than 10 dB RCS reduction in the frequency band from 9.8 GHz to 42.6 GHz with a relative bandwidth of 125.2% under normal incidence with arbitrary polarizations.