Improved Physical Theory of Diffraction: Removal of the Grazing Singularity

Physical theory of diffraction based on the concept of elementary edge waves [P. Ya. Ufimtsev, Electromagnetics, vol. 11, no. 2, pp. 125-160, 1991] is well suited for analysis of backscattering from perfectly conducting objects with edges. However, it needs to be improved for the investigation of forward scattering, especially in the directions grazing to the edge faces, where it predicts infinite values. The present paper removes this singularity by introducing a new definition for the uniform component of the surface current. This component is defined here as the current induced on the half-plane tangential to the illuminated face of the scattering edge (and to the edge itself). The improved theory of elementary edge waves is developed, which is valid for all scattering directions, including forward scattering