Effect of multilayer earth on wave propagation in overhead and underground transmission lines

In this paper, the method of Green´s function and operator technique is used to find the solution of the field equations of overhead and underground transmission lines in the presence of a semi-infinite N-layer non-perfect conducting earth. The solution gives an explicit analytical expression of the field in any of the layers produced by a line current located in a given layer. The expression involves a number of coefficients to be evaluated and a simple systematic procedure is presented for numerical computation of these coefficients. The solution obtained is a very general one in that there are no restrictions on the number and thickness of the layers, the properties of each layer and the location of the source. It is shown that existing solutions for N = 1, 2, 3 are merely special cases of the present solution.