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Title:  Efficient computational techniques for electromagnetic propagation and scattering 
Author(s):  Wagner, Robert Louis 
Doctoral Committee Chair(s):  Chew, Weng Cho 
Department / Program:  Engineering, Electronics and Electrical Engineering, Mechanical Physics, Electricity and Magnetism 
Discipline:  Engineering, Electronics and Electrical Engineering, Mechanical Physics, Electricity and Magnetism 
Degree Granting Institution:  University of Illinois at UrbanaChampaign 
Degree:  Ph.D. 
Genre:  Dissertation 
Subject(s):  Engineering, Electronics and Electrical
Engineering, Mechanical Physics, Electricity and Magnetism 
Abstract:  Electromagnetic propagation and scattering problems are important in many application areas such as communications, highspeed circuitry, medical imaging, geophysical remote sensing, nondestructive testing, and radar. This thesis develops several new techniques for the efficient computer solution of such problems. Most of this thesis deals with the efficient solution of electromagnetic scattering problems formulated as surface integral equations. A standard method of moments (MOM) formulation is used to reduce the problem to the solution of a dense, $N \times\ N$ matrix equation, where N is the number of surface current unknowns. An iterative solution technique is used, requiring the computation of many matrixvector multiplications. Techniques developed for this problem include the raypropagation fast multipole algorithm (RPFMA), which is a simple, nonnested, physically intuitive technique based on the fast multipole method (FMM). The RPFMA is implemented for twodimensional surface integral equations, and reduces the cost of a matrixvector multiplication from $O(N\sp2$) to $O(N\sp{4/3}$). The use of wavelets is also studied for the solution of twodimensional surface integral equations. It is shown that the use of wavelets as basis functions produces a MOM matrix with substantial sparsity. However, unlike the RPFMA, the use of a wavelet basis does not reduce the computational complexity of the problem. In other words, the sparse MOM matrix in the wavelet basis still has $O(N\sp2$) significant entries. The fast multipole methodfast Fourier transform (FMMFFT) method is developed to compute the scattering of an electromagnetic wave from a twodimensional rough surface. The resulting algorithm computes a matrixvector multiply in $O(N \log\ N$) operations. This algorithm is shown to be more efficient than another $O(N \log\ N$) algorithm, the multilevel fast multipole algorithm (MLFMA), for surfaces of small height. For surfaces with larger roughness, the MLFMA is found to be more efficient. Using the MLFMA, Monte Carlo simulations are carried out to compute the statistical properties of the electromagnetic scattering from twodimensional random rough surfaces. Finally, Liao's absorbing boundary condition (ABC) is studied in detail. This is an approximate ABC used to truncate the computational mesh in the finitedifference timedomain (FDTD) method. Unique results, both theoretical and numerical, are presented. 
Issue Date:  1996 
Type:  Text 
Language:  English 
URI:  http://hdl.handle.net/2142/23594 
Rights Information:  Copyright 1996 Wagner, Robert Louis 
Date Available in IDEALS:  20110507 
Identifier in Online Catalog:  AAI9625208 
OCLC Identifier:  (UMI)AAI9625208 
This item appears in the following Collection(s)

Dissertations and Theses  Electrical and Computer Engineering
Dissertations and Theses in Electrical and Computer Engineering 
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois