Design of an ultra-directive antenna using spatial coordinate transformation

Abstract

Spatial coordinate transformation is used as a reliable tool to control electromagnetic fields. In this paper, we derive the permeability and permittivity tensors of a metamaterial able to transform a dipole source radiating isotropically to an ultra-directive antenna. We show how its directivity is enhanced when the wavelength is sufficiently small compared to the width of the metamaterial. Numerical simulations using Comsol Multiphysics are performed to illustrate these properties.