Broadband wide-angle polarization-independent diffusion using parabolic-phase metasurface

Parabolic-phased profile was commonly utilized for concave or convex metalens. Here, we report for the first time using such approach for determinant and polarization-independent diffusion of scattering waves in broadband and wide incident angles by engineering parabolic-phased subarrays in coding sequences. For verification, a 1-bit metasurface is designed, across C, X, and Ku bands. Theoretical, numerical and experimental results demonstrate that our approach is very powerful in distributing the scattering energy more uniformly than available approach using non-gradient subarrays. The -7.5 dB fractional bandwidth is obtained as 88% and the diffuse scattering behavior can be preserved up to 60
^o
off normal incidence irrespective of polarizations. Our approach, simple and free of time-consuming optimizations, paves the way for electromagnetic compatibility and stealth applications under bistatic detection.