Ray optics for radiation problems in anisotropic regions with boundaries. I. Line-source excitation

Rigorous generic integral solutions for the fields radiated by phased-line distributions of electric or magnetic currents in the presence of two arbitrarily anisotropic half spaces are evaluated asymptotically by the saddle-point technique. The resulting field constituents are shown to be interpretable invariantly as geometric-optical (incident, reflected, and refracted) and diffracted (lateral-wave) contributions. These fields are then derived directly from ray-optical arguments, thereby providing a justification for this procedure without intervention of the rigorous formulation. Because of the general validity of ray-optical concepts in connection with asymptotic solutions in the far zone, use of ray techniques is then advocated also for more complicated configurations which are not amenable to rigorous analysis.