AN IMPROVED IMPEDANCE-BOUNDARY ALGORITHM FOR FOURIER SPLIT-STEP SOLUTIONS OF THE PARABOLIC WAVE-EQUATION

A new implementation of the previously published mixed Fourier transfo rm (MFT) method for including impedance boundaries in split-step parab olic equation solutions is described and demonstrated. The new algorit hm is formulated entirely in the discrete domain which results in exte nded applicability and increased computation speed. A brief review of the original MFT solution is followed by a detailed description of the discrete formulation. The performance of the new algorithm is then de monstrated with a few examples which rely heavily on the accuracy of t he impedance boundary. These examples include 10 MHz surface wave prop agation over smooth and rough sea surfaces and 18 GHz calculations uti lizing an effective rough surface impedance.