Calculation of Diffraction Field Using Incremental Theory of Diffraction for Observation Points Outside the Keller Cone

This letter presents an enhanced diffracted electromagnetic field calculation approach that addresses the critical limitations of conventional methods. Since traditional techniques, such as geometrical theory of diffraction, uniform theory of diffraction, and physical theory of diffraction, are constrained by infinite wedge assumptions, they fails to correctly calculate the electromagnetic field at observation points outside the Keller cone. In contrast, we implement the incremental theory of diffraction (ITD) for perfectly electrically conducting structures to accurately compute the diffraction field at arbitrary observation points through incremental integration along finite edges. The proposed hybrid methodology combines shooting-and-bouncing rays (SBR) with ITD for both multiple reflections and edge diffraction. Numerical simulations demonstrate significant performance improvements over conventional methods, particularly outside the Keller cone, where traditional techniques fail completely.