Corrections to fok's asymptotic form for the diffraction field close to a surface of variable curvature. II

Abstract

CORRECTIONS to Fok's asymptotic form for the wave field in a penumbra are calculated. Three problems are considered: plane wave diffraction at an impedance cylinder, cylindrical wave diffraction at a cylinder, and spherical wave diffraction at a solid of revolution. Corrections to Fok's asymptotic form were calculated in [1] for the field in a penumbra, when a plane wave is diffracted at an ideally reflecting cylinder or solid of revolution. In the present paper we extend the results obtained in [1] in several directions. We consider the problems of the oblique incidence of a plane wave on an impedance cylinder with variable impedance, the diffraction of a cylindrical wave at an ideally reflecting cylinder, and spherical wave diffraction at a solid of revolution. In all these cases the field in the penumbra is written as a principal term, expressed in terms of Fok's function, and two correction terms. Numerical examples show the accuracy of calculations of the field from our asymptotic relations.