Design of a Dichroic Transmissive Huygens' Metasurface Unit-Cell Presenting Refraction Angle Duality

TL;DR

This paper presents a theoretical and simulation-based design of a dual-band, dual-angle transmissive metasurface that refracts incident waves differently at two frequencies without reflections, using a circuit model of the unit cell.

Contribution

It introduces a circuit-based model for a dichroic Huygens' metasurface unit cell capable of dual-angle refraction at two frequency bands, validated through simulations and geometric analysis.

Findings

Circuit parameters can accurately predict refraction angles.

Simulation confirms the geometric structure approximates the circuit model.

The metasurface achieves dual-band, dual-angle refraction without reflections.

Abstract

A purely transmissive Huygens' metasurface model under plane-wave illumination is used to derive circuit parameters describing a constituent unit cell, such that diverse refraction angles are attained at two distinct frequency bands. Various levels of accuracy of the circuit description approaching the analytical are possible by constraining certain numbers of parameters. This theoretical study is then tested by calculating the exact formulas of the two representations for the various strategies proposed. By using simulations of a candidate unit-cell, we then examine whether such circuit parameters correspond to rudimentary versions of the geometry of a so-called parallel 'dogbone' structure. A device of this type is intended as dual-band (dichroic), dual-angle beam refractor diverting an incoming beam at different directions in two different bands without reflections.