Étude de modèles asymptotiques de la diffusion des ondes électromagnétiques par des interfaces naturelles - Application à une mer recouverte de pétrole -

Abstract : This work's topic is the electromagnetic wave scattering from one or two rough interfaces separating homogeneous media. One focuses more precisely on asymptotic models, which enable to solve the raised problem in a fast way, but in consequence have a restricted domain of validity.
For the case of a single interface, after a description of the existing methods, a detailed study of the so-called Kirchhoff' approximation is lead for the diffraction in reflection and transmission from a single interface. This method is reduced to the so-called geometric optics approximation, which is valid for strongly rough interfaces comparatively to the electromagnetic wavelength, in order to determine easily and rapidly the scattered power. The phenomenon of surface shadowing, which is well-known for the case of reflection, is not very familiar for the case of transmission ; that is why it is treated in details in this thesis.
For the case a rough layer, a bibliographical study of the existing methods allows us to notice the absence of methods based on the extension of the Kirchhoff' approximation to the case of two strongly rough interfaces. Thus, the method developed in this thesis overcomes this issue. This method is explained by assuming uncorrelated surfaces, in order to obtain a simple expression of the scattered power for numerical implementation. By comparison with a reference numerical method, the developed method is validated for a two-dimensional problem. An application to the detection of oil slicks over the sea surface is presented, and the method is extended to a three dimensional problem.
Document type :
Theses
Physics [physics]. Université de Nantes, 2006. French


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Contributor : Nicolas Pinel <>
Submitted on : Thursday, December 11, 2008 - 12:04:07 PM
Last modification on : Monday, October 26, 2009 - 9:07:21 AM

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Nicolas Pinel. Étude de modèles asymptotiques de la diffusion des ondes électromagnétiques par des interfaces naturelles - Application à une mer recouverte de pétrole -. Physics [physics]. Université de Nantes, 2006. French. <tel-00346259>

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