1 Introduction ................................................. 1
Part I Basics
2 Electromagnetic Fields ....................................... 5
2.1 Maxwell's Equations ..................................... 5
2.2 Material Equations ...................................... 6
2.3 Boundary Conditions ..................................... 8
2.4 Waves in Free Space ..................................... 9
2.5 Polarization ........................................... 11
2.6 Waves in Lossy Media ................................... 12
2.7 Energy Conservation .................................... 14
2.8 Electromagnetic Potentials ............................. 15
2.9 Green's Function ....................................... 17
2.10 Waves on Transmission Lines ............................ 18
3 Radiofrequency and Antenna Theory ........................... 23
3.1 Scattering Parameters .................................. 23
3.2 Resonators and Antennas ................................ 27
3.3 Antenna Parameters ..................................... 28
3.3.1 Antenna Radiation ............................... 28
3.3.2 Nearfield and Farfield .......................... 30
3.3.3 Radiation Pattern ............................... 31
3.3.4 Directivity, Efficiency and Gain ................ 33
3.3.5 Matching and Bandwidth .......................... 35
3.4 Antenna Arrays ......................................... 37
3.4.1 Farfield Approximation .......................... 37
3.4.2 Beam Steering ................................... 40
Part II Numerical Methods
4 Numerical Methods ........................................... 45
4.1 General Aspects of Numerical Modeling Software ......... 46
4.2 Finite-Difference Time-Domain (FDTD) ................... 48
4.2.1 Fundamentals .................................... 48
4.2.2 Discretization in Space and Time ................ 49
4.2.3 Numerical Stability and Dispersion .............. 54
4.2.4 Boundary Conditions ............................. 56
4.2.5 Excitations ..................................... 56
4.2.6 Circuit Parameters and Frequency-Domain
Quantities ...................................... 57
4.2.7 Nearfield-to-Farfield Transformation ............ 60
4.2.8 Prediction Filter for Structures with High
Q Value ......................................... 63
4.3 Method of Moments (MoM) ................................ 66
4.3.1 Fundamentals .................................... 66
4.3.2 Thin Wire Approximation ......................... 68
4.3.3 Metal Surfaces .................................. 70
4.3.4 Treatment of Dielectric Material ................ 71
4.3.5 Method of Moments for Layered Structures ........ 71
4.4 Finite-Element Method (FEM) ............................ 73
4.4.1 General Remarks ................................. 73
4.4.2 Variational Expression .......................... 73
4.4.3 Finite Elements ................................. 73
4.4.4 Shape Functions ................................. 74
4.4.5 Element Matrix .................................. 76
4.4.6 Matrix Compilation .............................. 76
4.4.7 Linear Systems .................................. 77
4.5 Other Methods .......................................... 78
5 Creating an Efficient Simulation Model ...................... 81
5.1 General Structure of Numerical Modeling Software ....... 81
5.1.1 Preprocessor .................................... 82
5.1.2 Solver .......................................... 83
5.1.3 Postprocessor ................................... 83
5.2 Geometry ............................................... 84
5.2.1 Interactive Construction via Graphical User
Interface (GUI) ................................. 84
5.2.2 Object Definition via Macro Language ............ 86
5.2.3 Import of CAD (Computer Aided Design) Data ...... 86
5.2.4 Summary ......................................... 88
5.3 Material Properties .................................... 89
5.4 Ports .................................................. 90
5.4.1 Waveguide Ports ................................. 91
5.4.2 Plane Wave Excitation ........................... 91
5.4.3 Lumped Ports .................................. 93
5.5 Lumped Circuit Elements ................................ 94
5.6 Boundary Conditions .................................... 94
5.6.1 Electric and Magnetic Walls ..................... 94
5.6.2 Absorbing Boundary Conditions ................... 96
5.7 Meshing ................................................ 97
5.7.1 Overview ........................................ 97
5.8 Simulation Control Parameters .......................... 99
5.9 Estimation of Required Resources ...................... 100
5.10 Postprocessing ........................................ 101
5.11 Selection of Numerical Method ......................... 102
5.12 Summary ............................................... 103
6 Canonical Examples ......................................... 107
6.1 Introduction .......................................... 107
6.2 Coaxial Line Discontinuity ............................ 108
6.2.1 Theoretical Background ......................... 108
6.2.2 Analysis with FDTD Software .................... 109
6.2.3 FDTD Convergence Study ......................... 115
6.2.4 Analysis with FEM Software ..................... 117
6.2.5 FEM Convergence Study .......................... 120
6.3 Coaxial Line Transition with Quarter Wavelength
Transformer ........................................... 123
6.3.1 Theoretical Background ......................... 123
6.3.2 Analysis with FDTD Software .................... 124
6.3.3 Analysis with FEM Software ..................... 126
6.4 Microstrip Filter ..................................... 128
6.4.1 Theoretical Background ......................... 128
6.4.2 Model Definition ............................... 130
6.4.3 Analysis with FDTD Software .................... 131
6.4.4 Analysis with FEM Software ..................... 135
6.4.5 Analysis with MoM Software ..................... 137
6.5 Feedpoint Impedance of a Dipole Antenna ............... 139
6.5.1 MoM Model Definition ........................... 139
6.5.2 MoM Convergence Study of Input Impedance and
Resonance Frequency ............................ 142
6.5.3 Transmission Between Distant Antennas .......... 143
6.5.4 Analysis with FDTD ............................. 144
6.5.5 Analysis with FEM Software ..................... 146
6.6 Aperture Antenna ...................................... 148
6.6.1 Rectangular Waveguide .......................... 148
6.6.2 Analysis with FDTD Software .................... 149
6.6.3 Analysis with FEM Software ..................... 155
6.7 Planar Inverted-F Antenna (PIFA) ...................... 157
6.7.1 General Remarks ................................ 157
6.7.2 Model Definition and FDTD-Based Antenna
Design ......................................... 158
6.7.3 Analysis with FEM Software ..................... 166
6.8 Induced Current Density in Lossy Media ................ 171
6.8.1 Model Definition ............................... 172
6.8.2 Convergence Study .............................. 174
6.9 Microstrip Gap in Resonant Cavity ..................... 177
6.9.1 Model Definition ............................... 177
6.9.2 Analysis with FEM .............................. 178
6.9.3 Analysis with FDTD ............................. 181
6.9.4 Analysis with MoM .............................. 183
6.9.5 FDTD Model with Lumped Port Excitation ......... 185
6.9.6 FDTD Model with Coaxial Port Excitation ........ 185
Part III Applications
7 Applications in Wireless Communications Systems ............ 191
7.1 GPS Antenna with Feeding Network ...................... 191
7.1.1 Background and Design Considerations ........... 191
7.1.2 Branchline Coupler Submodel .................... 193
7.1.3 Square Patch Antenna Submodel .................. 197
7.1.4 Combined Coupler and Antenna Model ............. 200
7.2 Base Station Antenna for Cellular Networks ............ 207
7.2.1 Introduction ................................... 207
7.2.2 Simple Model of a Base Station Antenna ......... 208
7.2.3 Validation ..................................... 211
7.2.4 Simple Base Station Antenna with Electrical
Downtilt ....................................... 213
7.2.5 Influence of Radome and Mounting Material ...... 215
7.2.6 Influence of Wall Mounting ..................... 216
7.2.7 Influence of Vertical Rotation ................. 218
7.2.8 Human Body in Front of Base Station Antenna .... 220
7.2.9 Conclusion ..................................... 224
7.3 Integrated Multiband Antennas for Mobile Phones ....... 225
7.3.1 Technical and Non-Technical Requirements ....... 226
7.3.2 Antenna Concepts ............................... 227
7.3.3 Detailed Analysis of the Functional Principle
of Mobile Phone Antennas ....................... 231
7.3.4 Interaction with the User ...................... 234
7.3.5 Midband Antenna Concepts ....................... 242
7.3.6 Summary ........................................ 245
7.4 Ultra-Wideband Antenna Design ......................... 247
7.4.1 Introduction ................................... 247
7.4.2 UWB Antenna Element Design and Optimization .... 248
7.4.3 The Influence of a Specific Integration
Scenario ....................................... 253
7.4.4 Establishing an Interface Between Different
Modeling Tools for the Entire System
Analysis ....................................... 256
7.4.5 Propagation Modeling and System Analysis ....... 264
7.4.6 Summary ........................................ 266
References .................................................... 269
Index ......................................................... 273
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