Radiation in Anisotropic Medium

Abstract

In this chapter, we will discuss the radiation characteristic of anisotropic medium by studying specifically dipole radiation from a uniaxially layered anisotropic media. We will calculate the far field radiation from an arbitrarily oriented Hertzian dipole when the dipole is placed over or embedded in a layered uniaxially anisotropic medium which is bounded above and below by isotropic media. The optic axis of the uniaxially anisotropic medium is arbitrarily oriented, i.e., not necessarily perpendicular to the plane of stratification. This leads to the cross-polarization effect and coupling between the ordinary and the extraordinary waves that exist in the anisotropic layer. The spectral domain approach is used to determine the far field behavior of the dipole. For this purpose, the dyadic Green’s functions (DGFs) derived in Chap. 4 will be used. The far-field approximated Green’s functions are evaluated using the method of stationary phase and the analytical results for the radiation fields are obtained for both horizontal (\( \hat{x} - {\hbox{ and }}\hat{y} - {\hbox{ oriented}} \)) and vertical (\( \hat{z} - {\hbox{ oriented}} \)) dipoles. The physical interpretation of the analytical results will also be discussed. In Sect. 5.5, numerical results are presented, including parameter studies on radiation patterns. In particular, the effects of anisotropy, layer thickness and dipole location on the radiation fields are discussed.