Electromagnetic Analysis of Anisotropic Impedance Spherical Metasurfaces

Abstract

We investigate the interaction of electromagnetic (EM) waves with a spherical conformal metasurface, described by a anisotropic surface impedance. To this end, a full-wave method is developed, based on the expansion of the fields in terms of spherical vector wave functions. Appropriate treatment of the anisotropic impedance boundary condition leads to sets of linear equations that allow for the determination of the involved EM fields. The developed method can be used for design and anal- ysis purposes, as well as for the study of metasurface-based EM scattering control. We examine a related application of a cloaking setup and show that anisotropy breaks the spherical symmetry and leads to interesting new effects, such as a polarization-dependent switch function. The presented results suggest that metasurfaces with appropriately engineered impedance tensors may lead to desired scattering responses that otherwise cannot be obtained with their isotropic counterparts.