Radiation of a circularly-polarized microstrip antenna through an uniaxial superstrate: A preliminary study

Abstract

Radiation by a microstrip patch antenna is well understood. Although typically such antennas are fed in a manner to achieve linear polarization, circular polarization is also of interest. Of more recent interest is the use of engineered composite materials (e.g. metamaterials) to control radiation. In some cases, inherently anisotropic materials have been characterized using isotropic inversion methods. Radiation through an isotropic material is fundamentally different than that of the true anisotropic material. In this paper, radiation of such an antenna through a uniaxial superstrate is investigated to demonstrate the hazard of using isotropic material properties for an inherently anisotropic material. One of the primary effects involves the distortion of radiated field polarization.Keywords-microstrip patch antenna; metamaterial; uniaxial superstrate; finite element method; measured material properties.