Book excerpt: The report presents a self-contained exposition of ground wave propagation over a smooth inhomogeneous earth model. A factorization procedure is used to obtain an exact solution for a two-dimensional cylindrical model which may have any number of homogeneous sections. It is demonstrated that under most conditions in practice, the solution for the mode conversion coefficients can be simplified to a form which was derived earlier by an application of the compensation theorem. Formulas are given which permit the refinement of earlier approximate calculations if such accuracy is required in future engineering developments such as precise navigation systems. (Author).