Abstract: This dissertation presents a Monte-Carlo multidomain pseudospectral time-domain (MPSTD) algorithm developed for the analysis of scattering from a two dimensional (2D) and three dimensional (3D) object buried below a random rough surface separating two half spaces. In the development, special attention is paid to the 3D computation domain decomposition, PML derivations, filtering technique and subdomain mapping involving the random rough surface as well as the subdomain patching along the rough surface. The Mote-Carlo MPSTD algorithm is then employed to determine the scattering of objects of various shapes and electromagnetic properties; embedded in the lower half space with different permittivity and the roughness of the random rough surface may vary. Sample numerical results are presented, validated, and analyzed. Then, scattering of objects buried in layered structure with random rough surface is studied using MPSTD algorithm. Through the analysis, it is observed that the roughness of the random rough surface and the electromagnetic properties of the lower half space can significantly affect the scattered signature of the buried object.

Contents:Light Scattering Problems in Astrophysics (J M Perrin)Surface Integral Operators and their Use in Acoustics and Electromagnetics (A Berthon)Acoustic Diffraction by Slender Bodies of Arbitrary Shape (M Tran-Van-Nhieu)High and Low Energy Approximations for the Electromagnetic Scattering by Irregular Objects (B Torresani)Electromagnetic Scattering and Mutual Interactions Between Closely Spaced Spheroids (J Dalmas & R Deleuil)Acoustical Imaging of 2D Fluid Targets Buried in a Half Space: A Diffraction Tomography Approach Using Line-Sources Insonification (B Duchene et al)Contribution of Radar Polarimetry in Radar Target Discrimination. The “Poincaré Planisphere”: a New Representation Method (E Pottier)Electromagnetic and Acoustic Waves in Random Media: from Propagation to Anderson Localization (B Souillard)Weak Disorder: Homogeneisation Method and Propagation (C Bardos)Coherent Propagation of Surface Acoustic Waves in Quasi-Periodic and Random Arrays of Grooves (D Sornette et al)On Asymptotic Behaviour of Waves States in Random Media (F Bentosela & R Rodriguez)A Study of Acoustic Transmission of Transient Signal in a Inhomogeneous Medium with the Help of a Wavelet Transform. Application to an Air-Water Plane Interface (G Saracco & Ph Tchamitchian)Three-Dimensional Impedance Scattering Theory (P Sabatier)Survey of Optimization Algorithms Applied to Inverse Problems (A Roger)A Linearized Inverse Problem: Acoustic Impedance Tomography of Biological Media (J P Lefebvre)and others Readership: Electrical engineers and mathematicians.

A general electromagnetic scattering formulation is presented for the situation in which a perfectly conducting body is embedded in a horizontally or radially stratified medium. The electric field integro-differential equation (EFIDE) and magnetic field integral equation (MFIE) are derived for the determination of the surface current density induced on the body by a general class of sources. Expressions are also presented for the use of the current density to determine the electric and magnetic fields scattered by the body into any layer of the medium. Detailed expressions for the MFIE and EFIDE are presented for the horizontally stratified two-layered medium configuration corresponding to the object being in a vacuum half-space above a lossy half-space. A computer code, which is an extended version of NEC-2A, is developed for the solution of the two-layer MFIE for a situation where the object is a model of an aircraft. Results corresponding to special cases obtained by this computer code are compared to experimental data as well as to numerical results obtained by another independently developed computer code.

The purpose of this investigation is to extend the capability of statistical modeling for the problem of electromagnetic scattering by random rough surfaces. A majority of prior studies considered the well known Gaussian joint probability density function (pdf), partly because of its mathematical convenience. About 25 years ago, a second pdf called exponential type was introduced and has since been used by several workers in the field. In this thesis it is shown that this exponential-type pdf fails to met an essential statistical requirement. To remedy this situation, an exponential pdf that satisfies all the statistical requirements is derived. The scattering properties of surfaces modeled by this new exponential pdf are then formulated. In the second part of this thesis a user-oriented computer program is developed to create random surfaces whose statistical description is at the will of the user requiring only the input of a monovariate pdf.