I. Introduction
One of the earliest studies of the propagation of electromagnetic waves along a finitely conducting, homogenous ground is due to Norton [1]. Later, Wait and his collaborators completed Norton's formulations and generalized them to the case of both horizontally and vertically stratified grounds. A historical and comprehensive review of the formulations, their domains of applicability, and theoretical bottlenecks, e.g., resulting from the presence of surface waves on “wrong” Riemann sheets were given in the review papers by Wait [2] [3]. It was shown how the concept of attenuation function can be used to represent the preferential attenuation of the higher frequencies of electromagnetic waves as they propagate along the surface of the ground [4].