Diffraction of a mode close to its cut-off by a transversal screen in a planar waveguide

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• 作者：A.V. Shanin ; ^{a.v.shanin@gmail.com} ; A.I. Korolkov
• 关键词：Waveguides ; Scattering ; Cut-off frequency ; Embedding formula ; Spectral equation
• 刊名：Wave Motion
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：68
• 期：Complete
• 页码：218-241
• 全文大小：649 K
• 卷排序：68

文摘

The problem of diffraction of a waveguide mode by a thin Neumann screen is considered. The incident mode is assumed to have frequency close to the cut-off. The problem is reduced to a propagation problem on a branched surface and then is considered in the parabolic approximation. Using the embedding formula approach, the reflection and transmission coefficients are expressed through the directivities of the edge Green’s function of the propagation problem. The asymptotics of the directivities of the edge Green’s functions are constructed for the case of small gaps between the screen and the walls of the waveguide. As the result, the reflection and transmission coefficients are found. The validity of known asymptotics of these coefficients is studied.