Simulation methods for predicting wave propagation over irregular terrain in the frequency ranges of VHF, UHF, and microwaves have been studied by many investigators. Those methods were applied to evaluate propagation path losses, coverage predictions, spectrum management, low altitude radar performance, microwave landing systems, etc. UTD ray models with digital terrain data simplified to two-dimensional (2-D) piecewise-linear profiles of wedges have been employed successfully to site-specifically determine terrain wave propagation. This article presents an automated method to simplify raw digital hilly terrain profiles into 2-D straight wedges and trapezoids (two consecutive wedges) based directly on the variations of the terrain elevations along a given vertical Tx-Rx profile. Also, a UTD ray approach for calculating all the forward diffraction from those piecewise-linear 2-D structures is proposed.
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