A Uniform Asymptotic Solution for Whispering Gallery Mode Radiation from a Cylindrically Curved Concave Conducting Surface

Keiji GOTO
Toshihide AJIKI
Toru KAWANO
Toyohiko ISHIHARA

Publication
IEICE TRANSACTIONS on Electronics   Vol.E90-C    No.2    pp.243-251
Publication Date: 2007/02/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e90-c.2.243
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Electromagnetic Theory and Its Application)
Category: High-Frequency Asymptotic Methods
Keyword: 
uniform geometrical theory of diffraction solution (UTD),  whispering gallery mode radiation,  electric type,  concave conducting surface,  

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Summary: 
When a cylindrically curved concave conducting surface is terminated abruptly at the edge, the whispering gallery (WG) mode propagating toward the edge direction is radiated into the free space from the aperture plane at the edge. In this paper, by applying the new analysis method, we shall derive a uniform geometrical theory of diffraction solution (UTD) for the electric-type WG mode radiation field applicable in the transition region near the geometrical boundaries produced by the incident modal ray on the edge of the curved surface. The UTD is represented by the summation of the solution for the geometrical ray converted from the modal ray of the WG mode and the solution for the uniform edge diffracted ray scattered at the cylindrically curved edge. By comparing with the reference solution obtained numerically from the integral representation of the radiation field, we will confirm the validity and the utility of the UTD proposed in this paper.