Coding Metasurface Combining Absorption and Diffusion for Broadband RCS Reduction

Here, a coding metasurface employing the hybrid mechanism of both absorption and diffusion is proposed for broadband radar cross section (RCS) reduction. The designed meta-atom combines an absorber, a polarization converter and a band-stop frequency selective surface (FSS), where the absorber absorbs the incident electromagnetic (EM) waves of low frequency, the polarization converter serves as the coding metasurface and diffuses the incident EM waves of high frequency, and the FSS isolates these two layers and serves as an equivalent ground of the polarization converter. In order to achieve diffuse scattering at high frequency, genetic algorithm is adopted to obtain optimal coding sequence. A metasurface with a size of 6.93λ 0 × 6.93λ 0 is designed to validate our methodology. Simulation results show the clear absorption effect from 1 GHz to 3 GHz and random diffusion from 4 GHz to 6 GHz, achieving a broadband 10 dB RCS reduction from 1 GHz to 3.2 GHz and 3.6 GHz to 6 GHz, with an average RCS reduction of 13.5 dB in the whole frequency band of 1 GHz to 6 GHz, which effectively demonstrates the proposed method, showing promising prospects in broadband stealth applications.