Coated Phase-Gradient Metasurfaces for Perfect Anomalous Reflection

Periodic phase-gradient metasurfaces (PGM) have been successfully used to produce anomalous reflection and refraction for small and moderate bending angles, but are not capable of efficiently producing wide-angle effects. For anomalous reflection, this limitation is overcome herein by coating the PGM with layered slabs of homogeneous (non-periodic) dielectrics, which serve to suppress the unwanted Floquet components of the scattered field. The required slab-widths of these multi-directional anti-reflective coatings (MDARC) are analytically determined for given dielectric constants, and their effects are verified by full-wave calculations. The PGM-MDARC combination provides a surprisingly simple structure for perfect anomalous reflection.