Tip Diffraction Coefficient of Wide-Angle Cones

We derive a new asymptotic procedure for the analysis of scalar wave diffraction by semi-infinite circular cones and apply it to derive a new closed-form expression for the tip-diffracted field in the wide-angle limit. The wide-angle cone is important, for example, for terrain or urban propagation. The phenomenological complexity of the wide-angle cone case, compared with the narrow-angle cone that has been solved in the past, is due to the profound role of the interplay between the tip diffraction and the geometrical optics reflections. The new formulation significantly simplifies the calculations and provides a cogent physical interpretation for the scattered field. The results are validated against the exact conical-harmonics solution.