Flat Transformation Optics

This paper presents an approach for the analysis of surface-wave (SW) propagation on modulated surface impedance described through a 2-D coordinate transformation. This approach is based on an extension of geometrical optics (GO) description for plane waves in graded index materials to SWs supported by modulated, impenetrable isotropic or anisotropic impedance boundary conditions. In particular, it extends to SWs the basic concepts of GO (ray-path, ray-velocity, transport of energy), thus, resulting in an elegant formulation which allows for close-form analysis of planar operational devices. Furthermore, being the modulated surface impedance based on 2-D coordinate mapping, it allows one to determine ray path without resorting to ray tracing.