Heuristic UTD Diffraction Coefficient for Three-Dimensional Dielectric Wedges
Takahiro Hashimoto, Xingqi Zhang, Costas D. Sarris
Abstract
This article presents a heuristic diffraction coefficient for 3-D dielectric wedges of arbitrary angles. First, the proposed diffraction coefficient is derived for 2-D wedges with soft and hard polarization, by enforcing continuity of the total field at every shadow boundary associated with the multiply reflected fields inside the wedge. The accuracy of the proposed heuristic 2-D solution is verified comparing with the UTD solution derived from Maliuzhinets' exact integration. Then, it is extended to 3-D wedges for arbitrary polarizations and incident/scattered directions by transforming ray-fixed to edge-fixed coordinate systems. The total field predicted using the proposed heuristic diffraction coefficient is continuous for arbitrary angle 3-D dielectric wedges, including interior wedges, and is close to the geometrical optics field far from the shadow boundaries. The proposed method is validated against a Method-of-Moment solution. Finally, we show the method can significantly improve the accuracy of ray-tracing modeling of wave propagation in arched tunnels.