A uniform asymptotic analysis of the diffraction by an edge in a curved screen

Abstract

An approximate asymptotic high-frequency solution is obtained for the electromagnetic wave diffraction by an edge in a curved conducting screen. The solution is uniform across the various ray shadow boundaries and is expressed in the simple format of the geometrical theory of diffraction. The transition functions associated with this uniform solution involve previously published special functions and can be calculated efficiently. Since the effect of the whispering gallery modes associated with the concave side of the curved screen is not included in this study, the present asymptotic solution is valid when neither the source nor the field points are close to the concave side of the screen. contract N60530-85-c-0249.

A generalized uniform geometrical theory of diffraction ray solution for the diffraction by a wedge with convex faces

“…Therefore this solution should be useful in many engineering applications. The present uniform (or UTD) solution was first published as a Ph.D. dissertation by Liang [1988]. It is noted that in a three-part paper, Michaeli [1989] presented a solution for the same two-dimensional curved wedge configuration as in this paper; however, his solution is only partially uniform.…”

“…The ansatz for the present solution is based on a uniform solution for the scattering by a curved screen [Chuang and Liang, 1988] when used together with the asymptotic matching technique. This new UTD solution contains more complicated transition functions than those present in the previous UTD edge diffraction solution, as one might expect.…”

A Uniform Geometrical Theory of Diffraction for Vertices Formed by Truncated Curved Wedges

“…Such residual ray discontinuities, if significant, together with the fact that a vanishing field is predicted in their associated ray shadow regions might render the resulting UTD description inaccurate. Therefore, higher order ray contributions must be added to complete the field description to remove the above deficiency, namely one may need to add vertex diffracted rays [9]- [14], doubly and triply wedge diffracted rays [15], [16], wedge diffraction of creeping waves [17], and wedge excited creeping wave ray fields [18], [19]. These contributions augment the asymptotic solution to higher orders outside their respective ray SB transition regions, and their uniform description restores the continuity of the field at the wedge diffracted and creeping wave-induced surface ray SBs.…”

A Novel UTD-Type Diffraction Coefficient for a Straight Edge in a Curved Screen

“…Idemen [14] and Serbest et al [15] obtained nonuniform solutions valid away from the edge transition regions. Chuang and Liang [16] and Michaeli [17] obtained uniform solutions in limited angular range of diffraction space by considering the problem of surface and edge diffractions in sequential manner.…”