A finite difference method for propagation predictions over irregular terrain

A novel method, based on the parabolic approximation, has recently been developed for predicting fields in an inhomogeneous atmosphere. Unlike its predecessors, it can be applied when the ground boundary is not horizontal, and it does not require the presence of an absorbing layer. This implicit finite-difference/Green´s function method (IFDG) is reviewed, and it is used to analyze the effect of a simple terrain irregularity on propagation within standard atmosphere. Its ability to easily provide coverage diagrams has been demonstrated. The method can also be used to analyze propagation over irregular terrain in nonstandard atmospheric environments, including those containing ducts with laterally changing properties.<>