Wavefront Control of 2D Curved Coding Metasurfaces Based on Extended Array Theory

We extend the array theory to design 2D curved coding metasurfaces in order to achieve arbitrary wavefront control. The extended array theory establishes the relationship between wavefront and curved-surface, which provides a simple and effective method to obtain the layout of desired metasurfaces. According the theory, we present 2D curved metasurfaces with 3-bit coding elements. Both simulations and measurements demonstrate that the proposed designs can manipulate wavefront effectively. For normal incidence, the aperture efficiency of normal reflection is more than 90%. For general oblique incidence, the proposed designs almost meet the expectances, but the aperture efficiency decreases with the increase of desired scattering elevation angle. The curved coding metasurfaces are expected to be applied to many devices such as conformal antenna array.