Using reflection and transmission coefficients to retrieve surface parameters for an anisotropic metascreen: With a discussion on conversion between TE and TM polarizations

Abstract

In recent work, we derived generalized sheet transition conditions (GSTCs) for electromagnetic fields at the surface of a metascreen (a metasurface with a "fishnet" structure, i.e., a periodic array of arbitrary spaced apertures in a relatively impenetrable surface). The effective electric and magnetic surface susceptibilities and surface porosities that appear explicitly in the GSTCs are uniquely defined and as such serve as the physical quantities that most appropriately characterize the metascreen. These surface parameters are related to the geometry of the apertures that constitute the metascreen and can exhibit anisotropic properties if this geometry is sufficiently asymmetric. These anisotropic properties can result in mode conversion between transverse electric (TE) and transverse magnetic (TM) polarizations when a plane-wave is incident onto a metascreen. Here, we use these GSTCs to derive the plane-wave reflection (R) and transmission (T) coefficients of an anisotropic metascreen, in which the coupling between TE and TM polarizations is illustrated. These expressions for R and T are used to develop a retrieval approach for determining the uniquely defined effective surface susceptibilities and surface porosities that characterize the metascreen from measured or simulated data. We present an example of a metascreen whose apertures are filled with a high-contrast dielectric, which shows interesting resonances at frequencies where no resonances exist when the apertures are not filled.

Generalized Sheet Transition Conditions for a Metascreen—A Fishnet Metasurface

“…In separate publications we use these GSTCs to derive the transmission (T ) and reflection (R) coefficients for an incident plane-wave onto a metascreen [36] and [37]. We show that with these T and R coefficients (determined either from numerical simulations or measurements) of a metascreen, we can derive a retrieval technique for obtaining the surface susceptibilities and surface porosises [36], which will give a method for uniquely characterizing the metascreen.…”

Retrieval Approach for Determining Surface Susceptibilities and Surface Porosities of a Symmetric Metascreen From Reflection and Transmission Coefficients

“…As seen from the GSTCs derived in [11] for the general case, the dyadic magnetic surface parameters may have offdiagonal terms such that coupling between transverse electric (TE) and transverse magnetic (TM) fields can occur [32]. To keep the analysis relatively simple, in this paper we will assume that the apertures are sufficiently symmetric that these off-diagonal terms are zero.…”

Using Generalized Sheet Transition Conditions (GSTCs) in the Analysis of Metasurfaces

“…(1.25) and (1.26) in the GSTCs (1.54) and (1.55), the reflection and transmission coefficients (as defined in Fig. 1.12) for a TE incident plane wave are obtained [39]:…”