An improved impedance-boundary algorithm for Fourier split-step solutions of the parabolic wave equation

A new implementation of the previously published mixed Fourier transform (MFT) method for including impedance boundaries in split-step parabolic equation solutions is described and demonstrated. The new algorithm is formulated entirely in the discrete domain which results in extended 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 demonstrated with a few examples which rely heavily on the accuracy of the impedance boundary. These examples include 10 MHz surface wave propagation over smooth and rough sea surfaces and 10 GHz calculations utilizing an effective rough surface impedance.