Diffraction by Plane Apertures in Uniaxially Anisotropic Media*

Abstract

A plane aperture is considered radiating in a uniaxially anisotropic medium that is otherwise assumed to be linear and homogeneous. A given but arbitrary aperture field distribution can be represented as the superposition of a transverse electric (TE) field and a transverse magnetic (TM) field relative to the direction of the optic axis of the medium. The existence of such a representation is used to show that once this decomposition is accomplished, the aperture illumination can be related to its corresponding diffraction field by considerations that involve only the propagation of electromagnetic waves in isotropic media. Considering the TE and TM fields separately, and beginning with existing diffraction formulas for each of these fields, the diffraction field may be obtained by solving two equivalent problems (one associated with the TE field and the other with the TM field), each of which requires the determination of a diffraction field produced by an illuminated aperture radiating in an isotropic medium. The well-known techniques and available results for apertures radiating in isotropic media may henceforth be applied to determine the diffraction fields produced by apertures radiating in uniaxially anisotropic media.