Hybrid cubic-chessboard metasurfaces for wideband angle-independent diffusive scattering and enhanced stealth

Because of the shortcomings associated with their scattering patterns, both the chessboard and cubic phased metasurfaces show non-perfect diffusion and hence sub-optimal radar cross section reduction (RCSR) properties. This paper presents a novel and powerful hybrid RCSR design approach for diffusive scattering by combining the unique attributes of cubic phase and chessboard phase profiles. The hybrid phase distribution is achieved by simultaneously imposing two distinct phase profiles (chessboard and cubic) on the hybrid metasurface area with the aid of geometric phase theory to further enhance the diffusive scattering and RCSR. It is shown in this paper that through the integration of cubic and chessboard phase profiles, a metasurface with the hybrid phase mask successfully overcomes all the above issues and shortcomings related to the RCSR of both chessboard and cubic metasurfaces. In addition, the proposed design leverages the unique scattering properties offered by these distinct phase profiles to achieve enhanced stealth capabilities over wide frequency ranges and for large incidence angles. Simulation and measurement results show that the designed hybrid metasurfaces using the proposed strategy achieved RCSR and low-level diffused scattering patterns from 12 – 28 GHz (80%) for normal incidence of a far-field CP radar plane wave. The hybrid metasurface show a stable angular diffusion and RCSR performance when the azimuthal and elevation incidence angles are in the range of 0^o → ±75^o which is wider than other designs in the literature. Therefore, this work can make objects significantly less detectable in complex radar environments when enhanced stealth is required.