The Method
of Moments in
Electromagnetics
Walton C. Gibson
http://www.tripointindustries.com
kalla@tripoint.org
Chapman & Hall/CRC
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Library of Congress Cataloging‑in‑Publication Data
Gibson, Walton C.
p. cm.
The method of moments in electromagnetics / Walton C. Gibson.
Includes bibliographical references and index.
ISBN 978‑1‑4200‑6145‑1 (alk. paper)
1. Electromagnetism‑‑Data processing. 2. Electromagnetic
fields‑‑Mathematical models. 3. Moments method (Statistics) 4. Electromagnetic
theory‑‑Data processing. 5. Integral equations‑‑Numerical solutions. I. Title.
QC665.E4.G43 2008
530.14’1015118‑‑dc22
2007037311
Visit the Taylor & Francis Web site at
http://www.taylorandfrancis.com
and the CRC Press Web site at
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Contents
Preface
Acknowledgments
About the Author
Chapter 1 Computational Electromagnetics
1.1 Computational Electromagnetics Algorithms
1.1.1 Low-Frequency Methods
1.1.2 High-Frequency Methods
References
Chapter 2 A Brief Review of Electromagnetics
2.1 Maxwell’s Equations
2.2 Electromagnetic Boundary Conditions
2.3 Formulations for Radiation
2.3.1 Three-Dimensional Green’s Function
2.3.2 Two-Dimensional Green’s Function
2.4 Vector Potentials
2.4.1 Magnetic Vector Potential
2.4.2 Electric Vector Potential
2.4.3 Comparison of Radiation Formulas
2.5 Near and Far Fields
2.5.1 Near Field
2.5.2
Far Field
2.6 Equivalent Problems
2.6.1
2.6.2
Surface Equivalent
Physical Equivalent
2.7 Surface Integral Equations
2.7.1 Electric Field Integral Equation
2.7.2 Magnetic Field Integral Equation
2.7.3 Combined Field Integral Equation
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Contents
References
Chapter 3 The Method of Moments
3.1 Electrostatic Problems
3.1.1 Charged Wire
3.1.2 Charged Plate
3.2 The Method of Moments
Point Matching
3.2.1
3.2.2 Galerkin’s Method
3.3 Common Two-Dimensional Basis Functions
Pulse Functions
Piecewise Triangular Functions
Piecewise Sinusoidal Functions
3.3.1
3.3.2
3.3.3
3.3.4 Entire-Domain Functions
3.3.5 Number of Basis Functions
3.4 Solution of Matrix Equations
3.4.1 Gaussian Elimination
3.4.2 LU Decompositon
3.4.3 Condition Number
3.4.4
Iterative Methods
3.4.5 Examples
3.4.6 Commonly Used Matrix Algebra Software
References
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Chapter 4 Thin Wires
4.6 Examples
4.1 Thin Wire Approximation
4.2 Thin Wire Excitations
4.2.1 Delta-Gap Source
4.2.2 Magnetic Frill
4.2.3
Plane Wave
4.3 Solving Hall´en’s Equation
4.3.1
Symmetric Problems
4.3.2 Asymmetric Problems
4.4 Solving Pocklington’s Equation
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Solution Using Triangle Basis and Testing Functions
75
Solution Using Sinusoidal Basis and Testing Functions 77
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Solution by Pulse Functions and Point Matching
4.5.1 Redistribution of EFIE Differential Operators
4.5.2
4.5.3
4.5.4 Lumped and Distributed Impedances
4.6.1 Comparison of Thin Wire Models
4.6.2 Circular Loop Antenna
4.6.3
Folded Dipole Antenna
4.6.4 Two-Wire Transmission Line
4.4.1
4.5 Thin Wires of Arbitrary Shape
Contents
4.6.5 Matching a Yagi Antenna
References
Chapter 5 Two-Dimensional Problems
5.1 Two-Dimensional EFIE
5.1.1 EFIE for a Strip: TM Polarization
5.1.2 Generalized EFIE: TM Polarization
5.1.3 EFIE for a Strip: TE Polariation
5.1.4 Generalized EFIE: TE Polarization
5.2 Two-Dimensional MFIE
5.2.1 MFIE: TM Polarization
5.2.2 MFIE: TE Polarization
5.3 Examples
5.3.1
5.3.2
References
Scattering by an Infinite Cylinder: TM Polarization
Scattering by an Infinite Cylinder: TE Polarization
Chapter 6 Bodies of Revolution
6.1 BOR Surface Description
6.2 Surface Current Expansion on a BOR
6.3 EFIE for a Conducting BOR
6.3.1 EFIE Matrix Elements
6.3.2 Excitation
6.3.3
Scattered Field
6.4 MFIE for a Conducting BOR
6.4.1 MFIE Matrix Elements
6.4.2 Excitation
6.4.3
Scattered Field
6.5 Notes on Software Implementation
6.5.1
Parallelization
6.5.2 Convergence
6.6 Examples
6.6.1 Galaxy
6.6.2 Conducting Sphere
6.6.3 EMCC Benchmark Targets
6.6.4 Biconic Reentry Vehicle
6.6.5
References
Summary of Examples
Chapter 7 Three-Dimensional Problems
7.1 Representation of Three-Dimensional Surfaces
7.2 Surface Currents on a Triangle
7.2.1 Edge Finding Algorithm
7.3 EFIE for Three-Dimensional Conducting Surfaces
7.3.1 EFIE Matrix Elements
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Contents
Singular Matrix Element Evaluation
7.3.2
7.3.3 EFIE Excitation Vector Elements
7.3.4 Radiated Field
7.4 MFIE for Three-Dimensional Conducting Surfaces
7.4.1 MFIE Matrix Elements
7.4.2 MFIE Excitation Vector Elements
7.4.3 Radiated Field
7.4.4 Accuracy of RWG Functions in MFIE
7.5 Notes on Software Implementation
7.5.1 Memory Management
7.5.2
Parallelization
7.6 Considerations for Modeling with Triangles
7.6.1 Triangle Aspect Ratios
7.6.2 Watertight Meshes and T-Junctions
7.7 Examples
Serenity
7.7.1
7.7.2 RCS of a Sphere
7.7.3 EMCC Plate Benchmark Targets
7.7.4
7.7.5 Bowtie Antenna
7.7.6 Archimedean Spiral Antenna
7.7.7
References
Summary of Examples
Strip Dipole Antenna
Chapter 8 The Fast Multipole Method
8.1 The Matrix-Vector Product
8.2 Addition Theorem
8.2.1 Wave Translation
8.3 FMM Matrix Elements
8.3.1 EFIE Matrix Elements
8.3.2 MFIE Matrix Elements
8.3.3 CFIE Matrix Elements
8.3.4 Matrix Transpose
8.4 One-Level Fast Multipole Algorithm
8.4.1 Grouping of Basis Functions
8.4.2 Near and Far Groups
8.4.3 Number of Multipoles
8.4.4
8.4.5 Transfer Functions
8.4.6 Radiation and Receive Functions
8.4.7 Near-Matrix Elements
8.4.8 Matrix-Vector Product
8.4.9 Computational Complexity
Sampling Rates and Integration
8.5 Multi-Level Fast Multipole Algorithm (MLFMA)
8.5.1 Grouping via Octree
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Contents
Interpolation Algorithms
8.5.2 Matrix-Vector Product
8.5.3
8.5.4 Transfer Functions
8.5.5 Radiation and Receive Functions
8.5.6
8.5.7 Computational Complexity
8.6 Notes on Software Implementation
Interpolation Steps in MLFMA
Initial Guess in Iterative Solution
8.6.1
8.6.2 Memory Management
8.6.3
Parallelization
8.6.4 Vectorization
8.7 Preconditioning
8.7.1 Diagonal Preconditioner
8.7.2 Block Diagonal Preconditioner
8.7.3
8.7.4
Inverse LU Preconditioner
Sparse Approximate Inverse
8.8 Examples
8.8.1 Bistatic RCS of a Sphere
8.8.2 EMCC Benchmark Targets
8.8.3
References
Summary of Examples
Chapter 9 Integration
9.1 One-Dimensional Integration
9.2
9.1.1 Centroidal Approximation
9.1.2 Trapezoidal Rule
9.1.3
Simpson’s Rule
9.1.4 One-Dimensional Gaussian Quadrature
Integration over Triangles
9.2.1
9.2.2 Radiation Integrals with a Constant Source
9.2.3 Radiation Integrals with a Linear Source
9.2.4 Gaussian Quadrature on Triangles
Simplex Coordinates
References
Index
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