Acknowledgments ................................................ xv
Introduction ................................................... xv
1 Survey of Small Antenna Theory ............................... 1
1.1 Introduction ............................................ 1
1.2 Small Antenna Parameters ................................ 3
1.2.1 Directivity ...................................... 3
1.2.2 Radiation Efficiency ............................. 4
1.2.3 Quality Factor ................................... 5
1.2.3.1 Antenna Quality Factor .................. 5
1.2.3.2 Quality Factor for Lumped Circuits ...... 6
1.2.3.3 External and Loaded Q .................. 11
1.2.4 Input Impedance and Matching .................... 12
1.3 Small Antenna Theory ................................... 13
1.3.1 Work of Wheeler (1947-1975) ..................... 16
1.3.1.1 The Radiation Power Factor ............. 16
1.3.1.2 The Spherical Coil ..................... 21
1.3.1.3 Comments ............................... 25
1.3.2 Work of Chu (1948) .............................. 26
1.3.2.1 Spherical Waves ........................ 26
1.3.2.2 Chu Equivalent Circuit ................. 27
1.3.2.3 Maximum Gain Omni-directional Chu
Antenna ................................ 30
1.3.2.4 Minimum Q Girini-directional Chu
Antenna ................................ 31
1.3.2.5 Maximum G/Q Omni-directional Chu
Antenna ................................ 31
1.3.2.6 Horizontally Polarized Omni-
directional Chu Antenna ................ 32
1.3.2.7 ТЕ and TM Circularly Polarized
Omni-directional Chu Antenna ........... 34
1.3.2.8 Comments ............................... 34
1.3.3 Work of Harrington (1960) ....................... 35
1.3.3.1 Maximum Gain for a Directional Chu
Antenna ................................ 35
1.3.3.2 Minimum Q for a Directional Chu
Antenna ................................ 36
1.3.3.3 Antenna Losses and Efficiency .......... 37
1.3.3.4 Comments ............................... 39
1.3.4 Work of Collin, Rothschild, and Fante(1964-
1969) ........................................... 39
1.3.4.1 Exact Q for a TM or ТЕ Propagating
Chu Antenna ............................ 39
1.3.4.2 Exact Q for a TM and ТЕ Propagating
Chu Antenna ............................ 41
1.3.4.3 Relationship Between Q and Fractional
Bandwidth В ............................ 43
1.3.4.4 Comments ............................... 46
1.3.5 Work of Hansen (1981-2006) ...................... 47
1.3.5.1 Closed Form Q for TM or ТЕ
Omni-directional Chu Antenna Using
Chu RLC Approximation .................. 47
1.3.6 Work of McLean (1996) ........................... 48
1.3.6.1 McLean's Exact Q for Chu Antenna
Radiating ТМю or ТЕ10 .................. 49
1.3.6.2 Q for Radiating Equally Excited ТМ10
and ТЕ10 ............................... 50
1.3.6.3 Exact Q for Chu Antenna Derived from
Mode Circuits .......................... 51
1.3.6.4 Comments ............................... 52
1.3.7 Work of Foltz and McLean (1999) ................. 52
1.3.7.1 Minimum Q for the TM Prolate Chu
Antenna ................................ 55
1.3.7.2 Comments ............................... 56
1.3.8 Work of Thiele (2003) ........................... 56
1.3.8.1 Superdirectivity and Q ................. 58
1.3.8.2 Comments ............................... 61
1.3.9 Work of Geyi (2003) ............................. 62
1.3.9.1 Field-Based Evaluation of Antenna Q .... 63
1.3.9.2 Reinvestigation of Small Antenna Gain
and Q Limitations ...................... 64
1.3.10 Work of Best (2003-2008) ........................ 68
1.3.10.1 By and Antenna Input Impedance ......... 69
1.3.10.2 Exact Q Derived from Maxwell's
Equations .............................. 71
1.3.10.3 Representing Q as a Function of
Antenna Input Impedance ................ 73
1.3.10.4 Fundamental Limitations on BV .......... 74
1.3.10.5 The Spherical Helix Antenna ............ 76
1.3.11 Work of Kwon and Pozar (2005-2009) .............. 78
1.3.11.1 Gain and Q for a Crossed-Dipole Chu
Antenna ................................ 80
1.3.11.2 Gain and Q for Dual-Set Chu Antenna
(DSCA) ................................. 82
1.3.12 Work of Thai (2006-2009) ........................ 83
1.3.12.1 Spherical Mode Circuits at the Chu
Sphere Surface ......................... 84
1.3.12.2 Q Value for the TMlm and TElm Modes .... 85
1.3.12.3 Self-Resonant Mode Configurations ...... 88
1.3.12.4 Thai's Energy Lower Bound on the
Mode Coupling Network .................. 93
1.3.12.5 Applications of the Energy Lower
Bound .................................. 96
1.3.13 Work of Gustafsson (2007) ....................... 97
1.3.13.1 Limitations on Small Antenna Gain-
Bandwidth Product and D/Q Ratio ........ 98
1.3.13.2 Applications of the Gustafsson
Limits ................................ 100
References ................................................. 104
2 Fundamental Limits and Design Guidelines for
Miniaturizing Ultra-Wideband Antennas ...................... 107
2.1 Introduction .......................................... 107
2.2 Overview of Fano-Bode Theory .......................... 108
2.3 Fano-Bode Limit for the Band-Pass Response ............ 112
2.4 Fano-Bode Limit for the High-Pass Response ............ 113
2.5 Antenna Miniaturization ............................... 117
2.5.1 Concept ........................................ 117
2.5.2 Dipole Antenna Example ......................... 118
2.6 Broadband Antenna Miniaturization ..................... 121
2.6.1 Optimal Miniaturization Factor ................. 122
2.6.2 Loading Profile ................................ 123
2.6.3 Equal LC Loading ............................... 127
2.7 Conclusion ............................................ 127
References ................................................. 128
3 Overview of Small Antenna Designs .......................... 131
3.1 Introduction .......................................... 131
3.2 Miniaturization via Shaping ........................... 132
3.2.1 Slot Loading ................................... 134
3.2.2 Bending and Folding ............................ 136
3.2.3 Space-Filling Curves ........................... 141
3.2.4 Meander Line Antennas .......................... 141
3.2.5 Fractal Antennas ............................... 143
3.2.6 Volumetric Antennas ............................ 149
3.2.7 Radio Frequency Identification Device
Antennas ....................................... l51
3.2.8 Small Ultra-Wideband Antennas .................. 153
3.2.9 Lumped Loading ................................. 156
3.3 Miniaturization via Material Loading .................. 160
3.3.1 Dielectric Materials ........................... 162
3.3.2 Magnetic Materials ............................. 167
3.3.3 Polymer Ceramic Material ....................... 170
3.4 Optimization Methods .................................. 180
3.4.1 Introduction ................................... 180
3.4.2 Genetic Algorithm .............................. 180
3.4.3 Particle Swarm Optimization .................... 185
3.5 Antennas on Electromagnetic Bandgap Ground Planes ..... 188
3.5.1 Performances Enhancement via Surface-Wave
Suppression .................................... 189
3.5.2 Low-Profile Antennas on EBG Ground Plane ....... 190
3.5.3 Wideband EBG Design ............................ 195
References ................................................. 199
4 Antenna Miniaturization via Slow Waves ..................... 209
4.1 Introduction .......................................... 209
4.2 Miniaturization Factor ................................ 210
4.3 Basic Antenna Miniaturization Concept ................. 211
4.3.1 Phase Coherent Radiation Conditions ............ 211
4.3.2 Equivalent Transmission Line (TL) Model of an
Antenna ........................................ 212
4.3.3 Artificial Transmission Line (ATL) of
Antennas ....................................... 213
4.4 Antenna Miniaturization Examples ...................... 220
4.4.1 Two-Wire Loop Antenna .......................... 220
4.4.2 Antenna Miniaturization by Increasing Shunt
Capacitance .................................... 222
4.4.2.1 Dielectric Loaded Patch Antenna ....... 222
4.4.3 Antenna Miniaturization by Increasing ATL
Series Inductance .............................. 224
4.4.3.1 Slotted Patches ....................... 224
4.4.3.2 Spiral with Coiled Arms ............... 226
4.4.4 Antenna Miniaturization by Increasing both
ATL Series Inductance and Shunt Capacitance .... 227
References ................................................. 231
5 Spiral Antenna Miniaturization ............................. 233
5.1 Spiral Antenna Fundamentals ........................... 233
5.1.1 Basic Planar Spiral Antenna Geometry ........... 233
5.1.2 Spiral Radiation ............................... 235
5.1.3 Input Impedance ................................ 236
5.1.4 Radiation Patterns ............................. 237
5.1.5 Radiation Phase Center ......................... 239
5.2 Truncation Effect in Finite Spiral Antennas ........... 241
5.3 Spiral Antenna Backed with a PEC Ground Plane ......... 244
5.4 Spiral Antenna Miniaturization Using Slow Wave
Treatments ............................................ 247
5.5 Spiral Miniaturization Using Dielectric Material
Loading (Shunt Capacitance) ........................... 249
5.6 Spiral Antenna Miniaturization Using Inductive
Loading (Series Inductance) ........................... 254
5.6.1 Planar Inductive Loading ....................... 254
5.6.2 Volumetric Inductive Loading ................... 257
5.7 Fabricated Miniature Spiral Antennas .................. 259
References ................................................. 265
6 Negative Refractive Index Metamaterial and
Electromagnetic Band Gap Based Antennas .................... 269
6.1 Introduction .......................................... 269
6.2 Negative Refractive Index Metamaterials ............... 270
6.2.1 Propagation in (ε < 0, μ < 0) Media ............ 270
6.2.2 Circuit Model of (ε < 0, μ < 0) Media .......... 273
6.2.3 Composite Circuit Model for the NRI-TL
Medium ......................................... 275
6.3 Metamaterial Antennas Based on NRI Concepts ........... 277
6.3.1 Leaky Wave Antennas ............................ 278
6.3.2 Miniature and Multi-band Patch Antennas ........ 287
6.3.3 Compact and Low-Profile Monopole Antennas ...... 291
6.3.4 Metamaterial-Inspired Antennas ................. 296
6.4 High-Gain Antennas Utilizing EBG Defect Modes ......... 300
References ................................................. 306
7 Antenna Miniaturization Using Magnetic Photonic and
Degenerate Band Edge Crystals .............................. 309
7.1 Introduction .......................................... 309
7.2 Slow Wave Resonances of MPC and DBE Crystals .......... 311
7.3 High Gain Antennas Embedded Within Finite Thickness
MPC and DBE Crystals .................................. 313
7.3.1 Transmission Characteristics of Finite
Thickness MPCs ................................. 313
7.3.2 Dipole Performance Within Magnetic Photonic
Crystal ........................................ 317
7.3.3 Resonance and Amplitude Increase Within DBE
Crystals ....................................... 320
7.3.4 Dipole Performance Within Degenerate Band
Edge Crystal ................................... 321
7.3.5 Practical Degenerate Band Edge Antenna
Realizations ................................... 325
7.4 Printed Antenna Miniaturization via Coupled Lines
Emulating Anisotropy .................................. 332
7.4.1 Antenna Miniaturization Using Degenerate Band
Edge Dispersion ................................ 332
7.4.2 Realizing DBE Dispersion via Printed Circuit
Emulation of Anisotropy ........................ 336
7.4.3 DBE Antenna Design Using Dual Microstrip
Lines .......................................... 339
7.4.4 Coupled Double Loop Antennas ................... 346
7.4.5 Printed MPC Antennas on Biased Ferrite
Substrates ..................................... 350
7.5 Platform/Vehicle Integration of Metamaterial
Antennas .............................................. 354
References ................................................. 357
8 Impedance Matching for Small Antennas Including Passive
and Active Circuits ........................................ 361
8.1 Introduction .......................................... 361
8.2 Passive Narrowband Matching ........................... 362
8.2.1 Dipole ......................................... 364
8.3 Passive Broadband Matching ............................ 368
8.3.1 Broadband Planar Dipole ........................ 369
8.3.2 Inverted Hat Antenna ........................... 372
8.4 Negative Matching ..................................... 374
8.4.1 Loop Antenna ................................... 374
8.4.2 Flare Dipole ................................... 380
8.5 Concluding Comments ................................... 385
References ................................................. 387
9 Antennas for RFID Systems .................................. 389
9.1 Historical Background ................................. 389
9.2 Basic Operation of RFID Systems ....................... 393
9.2.1 Tag Categories ................................. 393
9.2.2 Passive Radio Frequency Identifications ........ 394
9.2.2.1 RFID Microchip ........................ 395
9.2.2.2 Impedance Matching .................... 398
9.2.2.3 RFID Radar Cross Section .............. 399
9.3 Radio Frequency Identification Antennas ............... 400
9.3.1 Meander-Line Dipoles ........................... 400
9.3.2 Patch Antennas ................................. 401
9.3.3 Fractal Antennas ............................... 401
9.3.4 Planar Antennas ................................ 404
9.3.5 Slot Antennas .................................. 404
9.4 RFID Power Harvesting-Rectennas ....................... 405
References ................................................. 409
Index ......................................................... 413
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