Transition functions for high-frequency diffraction by a curved perfectly conducting wedge. III. Extension to overlapping transition regions

For pt.II see ibid., vol.37, no.9, p.1080-5(1989). The asymptotic theory of pt.II is extended to the case where the transition region of edge diffraction overlaps the region of surface diffraction. The extension is performed by incorporating Ufimtsev´s theory in the spectral domain approach. The dominant part of the scattered field is obtained by asymptotic evaluation of the radiation integral for the Fock current unperturbed by the edge, wherein the surface curvature and the finite distance to the field point are explicitly taken into account. The correction part, due to the fringed currents excited by the edge, is evaluated by the simpler procedure of pt.II. The dominant part involves a pair of new universal functions independent of the wedge angle. The coincide with those deduced in Pt.I from the rigorous canonical solution for a perfectly conducting cylindrically curved sheet. At very high frequencies, the present solution merges smoothly with the partially uniform solution of pt.II and with Keller´s solution in the appropriate angular domains of incidence and scattering