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

摘要

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.