Non-Periodic Metasurface for Retroreflection of Circularly Polarized Wave

In this work, we present a metasurface that can retroreflect the circularly polarized (CP) wave from a fixed oblique incidence angle. The metasurface is designed in non-periodic fashion, i.e., the entire surface is discretized by different elements with equal space. Each element is modeled by its unique phase response and will modify the wave front at different location for the reflected wave. The TE and TM phase response for one element are identical to maintain CP property upon reflection. By optimizing the phase distribution along the surface, strong back scattering is achieved in the retroreflection angle. This design method is verified by both full wave simulation and measurement at 10 GHz and can be easily reproduced to achieve other reflection properties, such as beam splitting and diffuse reflection.