Transformation Electromagnetics Devices Based on Printed-Circuit Tensor Impedance Surfaces

A method for designing transformation electromagnetics devices using tensor impedance surfaces (TISs) is presented. The method is first applied to idealized tensor impedance boundary conditions (TIBCs), and later to printed-circuit tensor impedance surfaces (PCTISs). A PCTIS is a practical realization of a TIBC. It consists of a tensor impedance sheet, which models a subwavelength patterned metallic cladding, over a grounded dielectric substrate. The method outlined in this paper allows anisotropic TIBCs and PCTISs to be designed that support tangential wave vector distributions and power flow directions specified by a coordinate transformation. As an example, beamshifting devices are designed, using TIBCs and PCTISs, that allow a surface wave to be shifted laterally. The designs are verified with a commercial full-wave electromagnetic solver. This work opens new opportunities for the design and implementation of anisotropic and inhomogeneous printed-circuit or graphene based surfaces that can guide or radiate electromagnetic fields.