Diffraction of TE waves by a metallic cap located on a dielectric sphere: Ring source excitation outside the sphere

Diffraction effects of a metallic cap located on a dielectric sphere on the propagation of high-frequency electromagnetic waves is investigated. The incident wave is supposed to be generated by a ring source located symmetrically with respect to the cap. Relying upon the locality principle of the GTD, the rigorous asymptotic solution is obtained by formulating the boundary-value problem in an abstract space in which the azimuth angle ? varies in the range ? ? (-?, ?). The application of an integral transform with kernel Q -1 v-1/2 (cos ?), having similar analytical properties with Fourier integral transform, yields a scalar Hilbert problem which can be solved asymptotically for |kr| » 1 and then, edge and surface diffraction coefficients are obtained. © 1998 Elsevier science B.V. All rights reserved