Deterministic Approach to Achieve Broadband Polarization-Independent Diffusive Scatterings Based on Metasurfaces

Abstract

Diffusive scatterings of electromagnetic (EM) waves by a thin screen are important in many applications, but available approaches cannot ensure uniform angular distributions of low-intensity scatterings without time-consuming optimizations. Here, we propose a robust and deterministic approach to design metasurfaces to achieve polarization-independent diffusive scatterings of EM waves within an ultrabroad frequency band and for wide-range of incident angles. Our key idea is to use high-efficiency Pancharatnam–Berry meta-atoms to form subarrays exhibiting focusing reflection-phase profiles, that can guarantee nearly uniform diffusive scatterings for arbitrarily polarized EM waves. As an illustration, we design and fabricate two metasurfaces and experimentally characterize their wave-diffusion properties in C, X, and Ku bands. Theoretical, numerical and experimental results demonstrate that our approach can diffuse the incident energy much more uniformly than available approaches based on the uniform-phase subarrays, thanks to the intrinsic wave-diffusion capabilities of the focusing-phase subarrays. The −7 dB fractional bandwidth is measured as 88.3% and the diffusive scattering behavior can be preserved up to 60° off-normal incidence irrespective of incident polarizations. Our approach, simple and robust, can help realize stealth applications under bistatic detections.