Perfect Anomalous Reflection with an Aggressively Discretized Huygens' Metasurface

This paper investigates the discretization of a periodic metasurface and demonstrates how such a surface can achieve perfect anomalous reflection. Whilst most contemporary theoretical works on metasurfaces deal with continuous current or impedance distributions, we examine how discretization affects a metasurface, and show that in some cases one can discretize a metasurface aggressively --- to the extent of having only two cells per spatial period. Such aggressive discretization can lead to great simplifications in metasurface design, and perhaps more surprisingly, a possible performance improvement from continuous metasurfaces. Using this aggressive discretization technique, we report the design of a binary Huygens' metasurface which reflects an incident plane wave at 50$^\circ$ into a reflected direction of -22.5$^\circ$. Full-wave electromagnetic simulation shows the achievement of anomalous reflection with a power efficiency of 99.1%, which dramatically surpasses the performance of a corresponding passive continuous metasurface, for which the power efficiency is fundamentally limited to 69.6%.