Reflection, Diffraction and Scattering at Low Grazing Angle of Incidence: Regular and Random Systems

Junichi NAKAYAMA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E94-C   No.1   pp.2-9
Publication Date: 2011/01/01
Online ISSN: 1745-1353
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Recent Progress in Electromagnetic Theory and Its Application)
Category: 
Keyword: 
reflection,  diffraction by periodic surface,  scattering by random surface,  shadow theory,  reciprocity,  guided wave,  

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Summary: 
When a monochromatic electromagnetic plane wave is incident on an infinitely extending surface with the translation invariance property, a curious phenomenon often takes place at a low grazing angle of incidence, at which the total wave field vanishes and a dark shadow appears. This paper looks for physical and mathematical reasons why such a shadow occurs. Three cases are considered: wave reflection by a flat interface between two media, diffraction by a periodic surface, and scattering from a homogeneous random surface. Then, it is found that, when a translation invariant surface does not support guided waves (eigen functions) propagating with real propagation constants, such the shadow always takes place, because the primary excitation disappears at a low grazing angle of incidence. At the same time, a shadow form of solution is proposed. Further, several open problems are given for future works.