Perfect Anomalous Reflection with a Binary Huygens' Metasurface

TL;DR

This paper introduces a simple, passive binary metasurface capable of perfectly redirecting electromagnetic waves into arbitrary directions with high efficiency, simplifying previous complex designs.

Contribution

The paper demonstrates that a binary Huygens' metasurface can achieve perfect anomalous reflection across wide angles and frequencies, using only two cells per period.

Findings

Achieves near-perfect anomalous reflection at 24 GHz

Works over a wide angular and frequency range

Simplifies metasurface design with only two cells per period

Abstract

In this paper we propose a new metasurface that is able to reflect a known incoming electromagnetic wave into an arbitrary direction, with perfect power efficiency. This seemingly simple task, which we hereafter call perfect anomalous reflection, is actually highly non-trivial due to the differing wave impedances and complex interference between the incident and reflected waves. Heretofore, proposed metasurfaces which achieve perfect anomalous reflection require complicated, deeply subwavelength and/or multilayer element structures which allow them to couple to and from leaky and/or evanescent waves. In contrast, we demonstrate that using a Binary Huygens' Metasurface (BHM) --- a passive and lossless metasurface with only two cells per period --- perfect anomalous reflection can be achieved over a wide angular and frequency range. Through simulations and experiments at 24 GHz, we show that a properly designed BHM can anomalously reflect an incident electromagnetic wave from $\theta_i = 50^\circ$ to $\theta_r = -22.5^\circ$, with perfect power efficiency to within experimental precision.