Cover image for Iterative and self-adaptive finite-elements in electromagnetic modeling
Title:
Iterative and self-adaptive finite-elements in electromagnetic modeling
Publication Information:
Boston, Mass. : Artech House, 1998
ISBN:
9780890068953

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30000004124438 QC760 I84 1998 Open Access Book Book
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Summary

Summary

This volume aims to assist readers in ensuring the accuracy of their results when applying the Finite Element Method (FEM) to electromagnetic and antenna problems. It outlines the method, describes its key elements and numerical techniques, and identifies various approaches to using the FEM in solving real-world microwave field problems.


Author Notes

Magdalena Salazar-Palma obtained a Ph.D. from the Universidad Politecnica de Madrid, Spain.

She is a professor titular in the Departmento de Senales, Sistemas y Radiocommunicaciones at the Universidad Politecnica de Madrid, Spain. She is a co-author of Iterative and Self-Adaptive Finite-Elements in Electromagnetic Modeling (Artech House, 1998). She is the chairperson of the Spain section of IEEE.

050


Table of Contents

Prefacep. xv
Acknowledgementsp. xix
List of Figuresp. xxi
List of Tablesp. xxxiii
Chapter 1 Introductionp. 1
1.1 Numerical Methods in Electromagneticsp. 1
1.1.1 Classification of Methods by Techniquep. 4
1.1.1.1 Analytical Methodsp. 4
1.1.1.2 Numerical Methodsp. 5
1.1.2 Classification of Numerical Methods by Type of Formulationp. 6
1.1.2.1. Methods Based on Partial Differential Equation Formulationsp. 6
1.1.2.2. Methods Based on Integral Formulationsp. 9
1.1.2.3. Comparison between Numerical Methodsp. 11
1.2 The Finite Element Method in Electromagneticsp. 12
1.2.1 Variational Calculus and Variational Methods of Approximationp. 15
1.2.2 The Origin of the Finite Element Method and Its Developmentp. 19
1.2.3 The Finite Element Method in the Field of Electromagnetic Engineeringp. 23
Chapter 2 The Finite Element Methodp. 25
2.1 Introductionp. 25
2.2 General Presentation of the Finite Element Method as Applied to Linear Boundary Value Problemsp. 26
2.3 Definition of the Continuous Problemp. 31
2.3.1 Definition of the Domain of the Problemp. 32
2.3.2 Classical or Strong Formulation of the Problemp. 36
2.3.3 Weak Formulation of the Problemp. 42
2.3.3.1. The Weighted Residual Methodp. 42
2.3.3.2. Variational Principlesp. 45
2.4 Discretization of an Integral Formp. 50
2.4.1 Approximation of a Functionp. 51
2.4.2 Discretization of a Weak Formulation or Variational Formulation of the Weighted Residual Typep. 52
2.4.3 Discretization of a Variational Principle: Ritz Methodp. 59
2.4.4 Convergence and Other Properties of the Variational Methods of Approximationp. 62
2.5 Discretization of the Continuous Problem by Means of the Finite Element Methodp. 63
2.5.1 Approximation of a Function by means of the Finite Element Methodp. 64
2.5.1.1 Discretization of the Domainp. 66
2.5.1.2 Description of the Finite Elementsp. 74
2.5.2 Discretization by the Finite Element Methodp. 115
2.5.2.1 Calculation of the Local Integral Forms: Numerical Integrationp. 119
2.5.2.2 Computation of the Global Integral Form: Assembly Processp. 123
2.5.2.3 Enforcement of the Essential Boundary Conditions: Global System of Equationsp. 127
2.5.2.4 Matrix Storage and Solution of the Global System of Equationsp. 128
2.5.2.5 Postprocessing of the Solutionp. 132
2.5.3 Convergence of the Finite Element Methodp. 134
2.6 Flow Diagram of a Finite Element Analysisp. 140
2.7 Public Domain and Commerical Software Packages for the Analysis of Electromagnetic Problems Utilizing the Finite Element Methodp. 140
Chapter 3 Application of the Finite Element Method to the Analysis of Waveguiding Problemsp. 145
3.1 Introductionp. 145
3.2 Quasi-Static Analysis of Transmission Linesp. 149
3.2.1 Description of the Structures to be Analyzedp. 150
3.2.2 Circuital and Electromagnetic Characterization of TEM and Quasi-TEM Multiconductor Transmission Linesp. 153
3.2.2.1 Two-Conductor Transmission Linep. 153
3.2.2.2 Multiconductor Transmission Line in an Inhomogeneous Anisotropic Medium with Dielectric and Magnetic Losses and Imperfect Conductorsp. 164
3.2.3 Application of the Finite Element Method to the Quasi-Static Analysis of Transmission Linesp. 168
3.2.3.1 Application of the Finite Element Method to the Direct Formulationp. 169
3.2.3.2 Application of the Finite Element Method to the Dual Standard Formulationp. 210
3.2.3.3 Application of the Finite Element Method to the Mixed Formulationp. 212
3.2.4 Conclusionsp. 215
3.3 Full-Wave Analysis of Waveguiding Structures Utilizing the Finite Element Methodp. 216
3.3.1 Description of the Geometry and Configuration of the Structures To Be Analyzedp. 217
3.3.2 Survey of Various Formulations of the Waveguiding Problem Utilizing the Finite Element Methodp. 217
3.3.3 Full-Wave Analysis of Waveguiding Structures Using the Finite Element Methodp. 221
3.3.3.1 Formulations Using Longitudinal Field Components: Lagrange Elementsp. 222
3.3.3.2 Formulations Using Transverse and Longitudinal Field Components: Lagrange/Curl-Conforming Elementsp. 227
3.3.4 Conclusionsp. 246
Chapter 4 Self-Adaptive Mesh Algorithmp. 247
4.1 Introductionp. 247
4.2 Self-Adaptive Techniques, Error Estimates, and Refinement Proceduresp. 248
4.3 Application of a Self-Adaptive Mesh Algorithm to the Quasi-Static Analysis of Transmission Linesp. 253
4.3.1 Local and Global Error Estimatesp. 254
4.3.2 Refinement Strategyp. 258
4.3.3 Element Subdivision Algorithmsp. 259
4.3.4 Self-Adaptive Algorithmp. 263
4.3.5 Validation of the Self-Adaptive Algorithmp. 264
4.4 Extension of the Self-Adaptive Algorithm to the Full-Wave Analysis of Waveguiding Structuresp. 283
4.5 Conclusionsp. 290
Chapter 5 Additional Examplesp. 291
5.1 Introductionp. 291
5.2 Quasi-Static Analysis of Transmission Linesp. 291
5.2.1 Finite-Thickness Coupled Microstrip Linesp. 291
5.2.2 Finite-Thickness Coupled Striplinesp. 293
5.2.3 Zero-Thickness Coupled Microstrip Linesp. 296
5.2.4 Three Coupled Microstrip Linesp. 298
5.2.5 Microstrip Line with Undercuttingp. 299
5.2.6 Symmetric Coplanar Waveguide with Broadside-Coupled Linesp. 300
5.2.7 V-Grooved Microstrip Linep. 304
5.2.8 Suspended Stripline with Supporting Groovesp. 305
5.2.9 Microstrip Line Near a Dielectric Edgep. 309
5.2.10 Electro-Optical Couplerp. 314
5.2.11 Dissipative Structuresp. 319
5.3 Full-Wave Analysis of Guiding Structuresp. 320
5.3.1 Shielded Microstrip Line: Case Ap. 320
5.3.2 Shielded Microstrip Line: Case Bp. 323
5.3.3 Shielded Microstrip Line: Effect of Wallsp. 323
5.3.4 Shielded Microstrip Line: Lossesp. 325
5.3.5 Bilateral Circular Finlinep. 325
5.3.6 Double Semicircular Ridge Guidep. 327
5.3.7 Coplanar Line with Anisotropic Substratep. 329
5.3.8 Microstrip Line with Anisotropic Substratep. 332
5.3.9 Finline with Anisotropic Substratep. 332
5.3.10 Suspended Coplanar Waveguidep. 334
5.3.11 Coupled Microstrip Linesp. 335
5.4 Conclusionsp. 335
Chapter 6 Application of Finite Element Method for the Solution of Open-Region Problemsp. 337
6.1 Introductionp. 337
6.2 Statement of the Problemp. 337
6.2.1 Introductionp. 337
6.2.2 The Finite Element Method and Open-Region Problemsp. 337
6.2.3 Nonlocal Boundary Conditionsp. 344
6.2.4 Comments on Solution of Linear Equationsp. 351
6.2.5 Applicationsp. 353
6.3 Two-Dimensional Electrostatic Problemsp. 353
6.3.1 Introductionp. 353
6.3.2 Formulationp. 354
6.3.3 Numerical Resultsp. 363
6.3.3.1 Circular Cylinderp. 363
6.3.3.2 Square Cylinderp. 365
6.3.3.3 Semicircular Cylinderp. 366
6.3.3.4 Bow-Tie Cylinderp. 368
6.3.4 Conclusionp. 369
6.4 TM Scatteringp. 370
6.4.1 Introductionp. 370
6.4.2 Formulationp. 371
6.4.3 Numerical Resultsp. 379
6.4.3.1 Elliptic Cylinderp. 379
6.4.3.2 Square Cylinderp. 382
6.4.3.3 Semicircular Cylinderp. 385
6.4.4 Conclusionp. 387
6.5 TE Scatteringp. 388
6.5.1 Introductionp. 388
6.5.2 Formulationp. 388
6.5.3 Numerical Resultsp. 395
6.5.3.1 Square Cylinderp. 395
6.5.3.2 Circular Cylinderp. 395
6.5.3.3 Semi-Circular Cylinderp. 398
6.5.4 Conclusionp. 400
6.6 Summaryp. 400
Chapter 7 Finite Element Analysis of Three-Dimensional Electromagnetic Problemsp. 401
7.1 Introductionp. 401
7.2 Spurious Modes and Curl-Conforming Elementsp. 401
7.2.1 Origin of Spurious Modesp. 402
7.2.1.1 Some Mathematical Concepts Related to the Spurious Modesp. 403
7.2.1.2 Some Early Ideas Regarding Spurious Modesp. 409
7.2.2 Solution to the Problem of Spurious Modesp. 411
7.2.2.1 At the Formulation Stagep. 412
7.2.2.2 At the Discretization Stagep. 415
7.3 Analysis of Three-Dimensional Cavity Resonances Using the Finite Element Methodp. 422
7.3.1 Finite Element Method Formulationp. 422
7.3.1.1 Variational Formulationp. 425
7.3.1.2 Discretization by Curl-Conforming Elementsp. 437
7.3.2 Dimension of the Vector Space Spanned by the Spurious Modesp. 442
7.3.3 Numerical Resultsp. 447
7.4 Analysis of Discontinuities in Waveguides Using the Finite Element Methodp. 460
7.4.1 Finite Element Formulationp. 461
7.4.1.1 Variational Formulationp. 461
7.4.1.2 Computation of the Scattering Parametersp. 465
7.4.2 Numerical Results: Application to Rectangular Waveguidesp. 466
7.4.3 Conclusionsp. 477
7.5 Analysis of Scattering and Radiation from Three-Dimensional Open-Regions Using the Finite Element Methodp. 480
7.5.1 The Methodp. 480
7.5.1.1 Introductionp. 480
7.5.1.2 Description of the Methodp. 481
7.5.1.3 Finite Element Formulation and Features of the Iterative Methodp. 483
7.5.2 Numerical Resultsp. 488
7.5.2.1 Radiationp. 488
7.5.2.2 Scatteringp. 489
7.5.3 Conclusionsp. 500
Appendix A A Mathematical Overviewp. 501
A.1 Some Concepts of Functional Analysisp. 501
A.1.1 Dimension of a Space. Finite-Dimensional Spacesp. 501
A.1.2 Functional Forms. Linear and Bilinear Operatorsp. 506
A.1.3 Hilbert and Sobolev Spacesp. 509
A.1.4 H(div,[Omega]) Spacesp. 517
A.1.5 H(curl,[Omega]) Spacesp. 518
A.1.6 H[superscript 1]([Omega])[times]H(curl,[Omega]) Spacep. 519
A.2 Weak Integral Formulations by the Weighted Residual Method: Integration by Parts. Essential and Natural Boundary Conditionsp. 520
A.3 An Overview of Variational Calculusp. 523
A.3.1 Variational Principles: Propertiesp. 523
A.3.2 Generalized, Complementary, and Mixed Variational Principles by Means of Lagrange Multipliersp. 527
Appendix B Definitions of Convergencep. 529
B.1 Types of Convergencep. 529
B.2 Some General Conclusions Regarding Convergencep. 531
Appendix C Topics Related to Finite Elementsp. 533
C.1 Mapping Between Parent Finite Elements and Real Finite Elements: Propertiesp. 533
C.2 Lagrange Ordinary Elementsp. 545
C.2.1 Rectangular Parent Elementsp. 545
C.2.2 Simplex Parent Elementsp. 546
C.3 Generation of One-Dimensional Infinite Elements for Asymptotic Approximation of the Unknown of Type (1/r)p. 547
C.4 Some Topics Related to Div-Conforming and Curl-Conforming Elementsp. 551
C.4.1 Div-Conforming Triangular Parent Elementsp. 551
C.4.1.1 First Order Elementsp. 551
C.4.1.2 Second Order Elementsp. 553
C.4.2 Curl-Conforming Simplex Parent Elementsp. 555
C.4.2.1 Triangular Elementsp. 555
C.4.2.2 Tetrahedral Elementsp. 564
C.4.3 On the Assembly of Div-Conforming and Curl-Conforming Elementsp. 567
C.5 Some General Conclusions Regarding the Use of Lagrange Elements, Div-Conforming and Curl-Conforming Elementsp. 572
C.5.1 Two-Dimensional Deterministic Problems. Quasi-Static Analysis of Transmission Lines. Lagrange Elements Versus Div-Conforming Elementsp. 572
C.5.2 Two-Dimensional Eigenvalue Problems. Full Wave Analysis of Waveguiding Structures. Lagrange Elements Versus Lagrange/Curl-Conforming Elementsp. 574
C.5.3 Three-Dimensional Problemsp. 576
Appendix D Maxwell's Equations in a Source-Free Region Specialized to Waveguiding Structuresp. 577
D.1 Introductionp. 577
D.2 Electromagnetic Characterization of Media in Electromagnetic Structuresp. 577
D.3 Steady-State Maxwell's Equations in a Source-Free Waveguiding Structurep. 582
D.3.1 Steady-State Maxwell's Equations in a Source-Free Structurep. 582
D.3.2 Specialization to Waveguiding Structuresp. 587
Appendix E Weak Formulations for the Quasi-Static Analysis of Waveguiding Structures and Their Finite Element Discretizationp. 597
E.1 Introductionp. 597
E.2 Direct Formulation. Lagrange Elementsp. 597
E.2.1 Weak Formulationp. 597
E.2.2 Discretization by Means of Lagrange Finite Elementsp. 601
E.3 Mixed Formulation. Div-Conforming Elementsp. 604
E.3.1 Weak Formulationp. 604
E.3.2 Discretization by Means of Div-Conforming Finite Elementsp. 607
Appendix F Weak Formulations for the Full-Wave Analysis of Waveguiding Structures and Their Finite Element Discretizationp. 613
F.1 Introductionp. 613
F.2 Formulation Utilizing the Longitudinal Components of the Electric and the Magnetic Fieldsp. 613
F.2.1 Inhomogeneous and Anisotropic Structuresp. 613
F.2.1.1 Weak Formulationp. 613
F.2.1.2 Discretization by Means of Lagrange Finite Elementsp. 622
F.2.2 Homogeneous and Isotropic Structuresp. 626
F.2.2.1 Weak Formulationp. 626
F.2.2.2 Discretization by Means of Lagrange Finite Elementsp. 630
F.3 Formulation Utilizing the Longitudinal and Transverse Components of the Electric or Magnetic Fieldp. 632
F.3.1 Standard Formulationp. 632
F.3.1.1 Weak Formulationp. 632
F.3.1.2 Discretization by Means of Lagrange/Curl-Conforming Elementsp. 639
F.3.2 Nonstandard Formulationp. 646
F.3.2.1 A Variant of the Previous Weak Formulationp. 646
F.3.2.2 Discretization by Means of Lagrange/Curl-Conforming Elementsp. 648
Appendix G Computation of Error Estimates and Indicatorsp. 651
G.1 Introductionp. 651
G.2 Computation of Local Error Estimates for the Quasi-Static Analysis of Transmission Lines Using the Direct Formulation and Lagrange Elementsp. 653
G.2.1 First-Order Straight Lagrange Triangular Elementp. 658
G.2.2 Second-Order Lagrange Triangular Elementp. 660
G.2.2.1 Straight or Subparametric Elementp. 660
G.2.2.2 Curved or Isoparametric Elementp. 663
G.2.3 Infinite Elements. Computation of the Residue at an Interface with an Ordinary Elementp. 667
G.2.3.1 First-Order Infinite Elementp. 670
G.2.3.2 Serendipity and Complete Second-Order Infinite Elementsp. 671
G.3 Computation of Local Error Indicators for the Full-Wave Analysis of Waveguiding Structuresp. 671
G.3.1 Formulation by Means of the Longitudinal Components of the Electric or the Magnetic Field and a Lagrange Element-Based Finite Element Methodp. 671
G.3.1.1 First-Order Lagrange Straight Triangular Elementp. 673
G.3.1.2 Second-Order Lagrange Straight Triangular Elementp. 674
G.3.2 Formulation by Means of the Transverse and Longitudinal Components of the Electric or Magnetic Field and a Lagrange/Curl-Conforming Element-Based Finite Element Methodp. 677
Bibliographyp. 697
Booksp. 697
Articlesp. 702
About the Authorsp. 743
Indexp. 745