| Eigenvalue Projection Theory for Linear Operator Equations of Electromagnetics |
SEP 87 |
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| Authors:
A. F. Peterson; ILLINOIS UNIV AT URBANA COORDINATED SCIENCE LAB
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 | Equations representing realistic electromagnetics problems seldom yield exact solutions, and thus are usually treated numerically. In general, a discretization procedure such as the method of moments (also known as the weighted residual method) is used to convert the original continuous equation to a finite-dimensional matrix equation. A theory is presented that demonstrates the relation between the eigenvalue spectrum of the original, continuous operator and the eigenvalues of the method-of-moments matrix. ... |
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| Mutual Admittance between Slots in Cylinders of Arbitrary Shape |
AUG 87 |
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| Authors:
A. F. Peterson; R. Mittra; ILLINOIS UNIV AT URBANA COORDINATED SCIENCE LAB
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| A numerical procedure to estimate the mutual admittance between finite slots in infinite, conducting cylinders of arbitrary cross-sectional shape is described. The problem formulation involves a fourier transform and the numerical solution of integral equations. Additional issues addressed include the large amount of required computation, remedies for non-uniqueness problems associated with the integral equations, and the overall accuracy of the procedure. Good agreement is obtained between the numerical results and ... |
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| Mutual Admittance between Slots in Cylinders of Arbitrary Cross Section Shape, |
FEB 1987 |
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| Authors:
A. F. Peterson; R. Mittra; ILLINOIS UNIV AT URBANA ELECTROMAGNETIC COMMUNICATION LAB
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| Both the proper design of slot arrays and the positioning of multiple antenna arrays on a common surface require an accurate estimate of the mutual coupling between individual slot elements. To date, the analysis of mutual admittance has been undertaken for slot elements in simple shapes such as circular cylinders, cones, and spherical surfaces. Limited attempts have also been made to treat more general surface shapes using asymptotic methods. In ... |
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| An Analysis of the Spectral Iterative Technique for Electromagnetic Scattering from Individual and Periodic Structures |
OCT 86 |
45 pages |
| Authors:
A. F. Peterson; ILLINOIS UNIV AT URBANA ELECTROMAGNETIC COMMUNICATION LAB
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 | It is shown that the discrete system solved by the Spectral Iterative Technique (SIT) is of Toeplitz or block Toeplitz form, and thus may be more amenable to direct solution in certain cases. In addition, the discrete system associated with the SIT is shown to be equivalent to a moment method matrix equation, with basis and testing functions chosen implicitly in the process. Thus, there is no additional generality in ... |
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| On the Implementation and Performance of Iterative Methods for Computational Electromagnetics |
DEC 85 |
199 pages |
| Authors:
A. F. Peterson; R. Mittra; ILLINOIS UNIV AT URBANA ELECTROMAGNETIC COMMUNICATION LAB
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| The numerical solution of electromagnetic scattering problems involves approximating an exact equation by a finite-dimensional matrix equation. The use of an iterative algorithm to solve the matrix equation sometimes results in a considerable savings in computer memory requirements. For a fixed amount of computer memory, this approach permits the analysis of scatterers that are an order of magnitude larger electrically. Iterative algorithms of the conjugate gradient class are examined and ... |
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| The Method of Conjugate Gradients for the Numerical Solution of Large- Body Electromagnetic Scattering Problems |
MAR 85 |
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| Authors:
A. F. Peterson; R. Mittra; ILLINOIS UNIV AT URBANA COMPUTER SYSTEMS GROUP
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| Over the past few decades, many techniques have been developed for the numerical solution of integral equations representing electromagnetic scattering problems. However, a majority of these techniques are limited to electrically small scatterers, i.e., below the resonance range. This is primarily because the amount of CPU computer time and storage requirements become prohibitive for large body scatterers. Recent work indicates that a procedure based on the iterative conjugate gradient method ... |
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| Study of Numerical Methods in Seismic Problems, |
07 SEP 1972 |
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| Authors:
D. W. McCowan; C. A. Newton; E. A. Page; A. F. Peterson; E. A. Flinn; TELEDYNE GEOTECH ALEXANDRIA VA ALEXANDRIA LABS
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| The authors investigate the application of two numerical methods (finite element and finite difference approximations) toward the ultimate solution of problems involving the propagation of Rayleigh waves generated by an explosion in the atmosphere over an island atoll. Because of mathematical difficulties in these methods, useful calculations of Rayleigh wave spectra at teleseismic diatances were not obtained. It appears that the physical constraints of the atoll structure, e.g., abrupt changes ... |
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