Coding metasurface for broadband microwave scattering reduction with optical transparency

TLDR

Metasurfaces enable full control of electromagnetic wavefronts by spatially manipulating phase across an interface. The authors propose a flexible, sub‑wavelength ITO coding metasurface that achieves broadband backward scattering reduction via diffusion‑like microwave reflection. This effect arises from destructive interference of far‑field waves caused by randomly distributed reflection phases encoded in pre‑designed meta‑atoms arranged with a pseudorandom sequence. Simulations and measurements confirm that the metasurface delivers polarization‑independent 10 dB scattering reduction from 8 to 15 GHz, retains performance when wrapped around a metallic cylinder, and maintains high visible‑frequency transmittance, making it suitable for windows and solar panels.

Abstract

Metasurfaces have promised great possibilities in full control of the electromagnetic wavefront by spatially manipulating the phase characteristics across the interface. Here, we report a scheme to realize broadband backward scattering reduction through diffusion-like microwave reflection by utilizing a flexible indium-tin-oxide (ITO)-based ultrathin coding metasurface (less than 0.1 wavelength thick) with high optical transparence. The diffusion-like scattering is caused by the destructive interference of the scattered far-field electromagnetic wave, which is further attributed to the randomly distributed reflection phases on the metasurface composed of pre-designed meta-atoms arranged with a computer-generated pseudorandom coding sequence. Both simulation and measurement on fabricated prototype sample have been carried out to validate its performance, demonstrating a polarization-independent broadband (nearly from 8 GHz to 15 GHz) 10 dB scattering reduction with good oblique performance. The excellent performances can also be preserved to conformal cases when the flexible metasurface is uniformly wrapped around a metallic cylinder. The proposed metasurface may create new opportunities to tailor the exotic microwave scattering features with simultaneously high transmittance in visible frequencies, which could provide crucial benefits in many practical uses, such as window and solar panel applications.