COMPUTATIONAL METHODS
FOR ELECTROMAGNETICS
IEEElOUP SERIES ON ELECTROMAGNETIC WAVETHEORY
The IEEE/OUPSeries on Electromagnetic Wave Theoryconsistsof new titles as well as
reprintings and revisions of recognized classics that maintainlong-term archival signifi
cance in electromagnetic waves and applications.
Series Editor
DonaldG. Dudley
University of Arizona
Advisory Board
RobertE. Collin
CaseWestern Reserve University
AkiraIshimaru
University of Washington
D.S. Jones
University of Dundee
Associate Editors
Electromagnetic Theory, Scattering, and Diffraction
Ehud Heyman
Tel-Aviv University
Differential Equation Methods
AndreasC. Cangellaris
University of Illinois
Integral Equation Methods
Donald R. Wilton
University of Houston
Antennas, Propagation, and Microwaves
DavidR. Jackson
University of Houston
BOOKS IN THE IEEFlOUP SERIES ON ELECTROMAGNETIC WAVETHEORY
Chew, W. C., Waves and Fields in Inhomogeneous Media
Christopoulos, C., The Transmission-Line Modeling Methods: TLM
Clemmow, P. C., The PlaneWave Spectrum Representation ofElectromagnetic Fields
Collin,R. E., FieldTheory ofGuidedWaves, Second Edition
Dudley, D. G., Mathematical Foundations for Electromagnetic Theory
Elliot, R. S., Electromagnetics: History, Theory, and Applications
Felsen,L. B., and Marcuvitz, N., Radiation and Scattering o/Waves
Harrington, R. F., FieldComputation by MomentMethods
Jones, D. S., Methods in Electromagnetic Wave Propagation, SecondEdition
Lindell, I. V., Methods for Electromagnetic FieldAnalysis
Tai,C. T., Generalized Vector and DyadicAnalysis: AppliedMathematics in FieldTheory
Tai,C. T., DyadicGreen Functions in Electromagnetic Theory, SecondEdition
Van Bladel,J., SingularElectromagnetic Fields and Sources
Wait, J., Elecromagnetic Waves in Stratified Media
COMPUTATIONAL METHODS
FOR ELECTROMAGNETICS
---,~---
IEEE PRESS Series on
Electromagnetic Waves
Andrew F. Peterson
School ofElectricaland Computer Engineering
Georgia Institute ofTechnology
Scott L. Ray
Modeling and Information Sciences Laboratory
Dow AgroSciences
Raj Mittra
Department ofElectrical and Computer Engineering
Pennsylvania State University
IEEE Antennas & Propagation Society, Sponsor
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ISBN 0-7803-1122-1
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Library of Congress Cataloging-in-Publication Data
Peterson, Andrew F., 1960-
Computational methods for electromagnetics / Andrew F. Peterson,
Scott L. Ray, Raj Mittra.
p.
cm.
"IEEE Antennas & Propagation Society, sponsor.ft
"IEEE Press series on electromagnetic waves."
Includes bibliographic references and index.
ISBN 0-7803-1122-1
1. Electromagnetism. 2. Numerical analysis.
I. Ray,Scott L.,
.
II. Mittra, Raj.
1957-
Society.
IV. Title.
QC760.P48
1997
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III. IEEE Antennas and Propagation
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Contents
PREFACE xvii
ACKNOWLEDGMENTS xix
CHAPTER 1 ELECTROMAGNETIC THEORY 1
I
10
4
6
1.1 Maxwell's Equations
1.2
1.3
1.4
1.5
1.6
1.7
Volumetric Equivalence Principle for Penetrable Scatterers
General Description of a Scattering Problem 5
Source-Field Relationships in Homogeneous Space
Duality Relationships
Surface Equivalence Principle
Surface Integral Equations for Perfectly
Conducting Scatterers
Volume Integral Equations for Penetrable Scatterers
Surface Integral Equations for Homogeneous Scatterers
1.8
1.9
1.10 Surface Integral Equation for an Aperture
10
16
18
19
in a Conducting Plane
22
1.11 Scattering Cross Section Calculation
24
1.12 Scattering Cross Section Calculation
for Two-Dimensional Problems
for Three-Dimensional Problems
1.13 Application to Antenna Analysis
1.14 Summary
References
Problems
30
30
31
27
28
vii
viii
Contents
CHAPTER 2 INTEGRAL EQUATION METHODS
FOR SCATTERING
FROM INFINITE CYLINDERS 37
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
50
TM-Wave Scatteringfrom ConductingCylinders:
EFIE Discretized with Pulse Basis and Delta
Testing Functions 37
TE..Wave Scattering from ConductingCylinders:
MAE Discretized with Pulse Basis and Delta
TestingFunctions 45
Limitationsof Pulse BasislDelta
TestingDiscretizations
TE..Wave Scattering from Perfectly Conducting
Stripsor Cylinders: EFIE Discretized withTriangle
Basis and Pulse TestingFunctions 52
TM..Wave Scatteringfrom Inhomogeneous Dielectric
Cylinders:Volume EFIE Discretizedwith Pulse
Basis and Delta TestingFunctions 59
TE-Wave Scattering from DielectricCylinders: Volume
EFIE Discretized with Pulse Basis and Delta
TestingFunctions 65
TE-Wave Scatteringfrom Inhomogeneous Dielectric
Cylinders:Volume MFIE Discretized with Linear Pyramid
Basis and Delta TestingFunctions 70
Scattering fromHomogeneous Dielectric Cylinders: Surface
Integral Equations Discretized with Pulse Basis and Delta
Testing Functions 76
Integral Equations for Two-Dimensional Scatterers Having
an ImpedanceSurface 80
2.10 Summary 85
85
References
Problems 86
CHAPTER 3 DIFFERENTIAL EQUATIONMETHODS
FOR SCATTERING
FROM INFINITE CYLINDERS 95
3.1 WeakForms of the Scalar HelmholtzEquations 95
3.2
3.3
Incorporation of PerfectlyConducting Boundaries 98
Exact Near-ZoneRadiationCondition
on a Circular Boundary 100
3.4 Outward-Looking Formulation Combining
the Scalar HelmholtzEquation with the Exact
Radiation BoundaryCondition 102
Example: TM-Wave Scattering
from a DielectricCylinder
106
3.5
ConWn~
~
3.6
3.7
3.8
3.9
110
112
Scattering from Cylinders Containing Conductors
Evaluation of Volumetric Integrals
for the Matrix Entries
Local Radiation Boundary Conditions on a Circular
Surface: The Bayliss-Turkel Conditions
Outward-Looking Formulation Combining the Scalar
Helmholtz Equation and the Second-Order
Bayliss-Turkel RBC 120
115
3.10 Exact Near-Zone Radiation Boundary Conditions
for Surfaces of General Shape
125
3.11 Connection between the Surface Integral
3.12
3.13
128
and Eigenfunction RBCs
Inward-Looking Differential Equation Formulation:
The Unimoment Method
Summary
References
Problems
135
136
130
137
CHAPTER 4 ALGORITHMS FOR THE SOLUTION
OF LINEAR SYSTEMS OF EQUATIONS 143
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
143
146
149
146
Naive Gaussian Elimination
Pivoting
Condition Numbers and Error Propagation
in the Solution of Linear Systems
Cholesky Decomposition
for Complex-Symmetric Systems
Reordering Algorithms for Sparse Systems
of Equations
Banded Storage for Gaussian Elimination
Variable-Bandwidth or Envelope Storage
for Gaussian Elimination
Sparse Matrix Methods Employing Dynamic
Storage Allocation
Frontal Algorithm for Gaussian Elimination
Iterative Methods for Matrix Solution
160
156
158
150
4.9
4.10
4.11 The Conjugate Gradient Algorithm
161
for General Linear Systems
156
159
4.12 The Conjugate Gradient-Fast Fourier Transform
170
(CG-FFf) Procedure
Fast Matrix-Vector Multiplication: An Introduction
to the Fast Multipole Method
Preconditioning Strategies for Iterative Algorithms
Summary
175
179
4.13
4.14
4.15
178