Ground-Wave Propagation Over a Non-Homogeneous Earth

Abstract

Till a few years back, the only method that was available for calculating the ground-wave field-strength at a point, when the propagation path consisted of well-defined sections of widely differing ground constants, was the one proposed by P. P. Eckersley in 1930.¹ The Eckersley method rarely gave results which agreed with measured values and hence was considered unsatisfactory. During recent years, a number of methods have been proposed for calculation of ground-wave field-strength over a non-homogeneous earth. Of these, the method proposed by G. Millington⁴ has been found to give sufficiently accurate results under all conditions of propagation, and has been generally accepted as the most dependable method, among those published till now. This paper explains the various methods which have been proposed, discusses three of the more recognized ones in detail, and then proceeds to judge the relative merits of these three methods, based on available measured data. An independent conclusion is arrived at, which only corroborates the view regarding the superiority of the Millington method. Certain effects associated with non-homogeneous propagation are also discussed and their practical importance indicated.