UTD based prediction of propagation loss over spherical earth surface

An effective modeling of wave propagation over the spherical earth surface is of importance for target tracking, radar detection and wireless system analysis. This topic has been intensively studied in the past several decades (V. A. Fock, Electromagnetic Diffraction and Propagation Problems, Oxford: Pergamon, 1965). Meanwhile, the uniform theory of diffraction (UTD) for smooth convex surfaces has been developed and widely used in electromagnetic radiation and scattering. However, applying UTD to an effective analysis of propagation over a spherical earth surface still remains a challenge so far.