Multiband Integrated Antennas for 4G Terminals David A. Sanchez-Hernandez Universidad Politecnica de Cartagena Editor f ARTECH HOUSE BOSTON LONDON artechhouse.com
Contents Foreword Preface xi xiii CHAPTER 1 Electrically Small Multiband Antennas 1 1.1 Introduction 1 1.2 The Definition of Electrically Small 2 1.3 Fundamental Antenna Properties Definitions 3 1.3.1 Impedance, Efficiency, VSWR, and Gain 3 1.3.2 Bandwidth and Quality Factor (Q) 6 1.4 Fundamental Limits of Small Antennas 10 1.5 Special Considerations for Integrated Multiband Antennas 12 1.6 Fundamental Approaches to Small Integrated Antenna Design 16 1.6.1 The Monopole Antenna 16 1.6.2 The Inverted-L Antenna 17 1.6.3 The Inverted-F and Planar Inverted-F Antennas 18 1.7 Finite Ground Plane Effects on Small Antenna Performance 22 References 30 CHAPTER 2 Multiband Multisystem Antennas in Handsets 33 2.1 Introduction 33 2.1.1 Frequencies and Systems 33 2.1.2 Typical Specifications 36 2.2 Multiband Techniques 36 2.2.1 Radiating and Balanced Mode Theory 37 2.2.2 Analysis of PIFA Slots 41 2.2.3 Analysis of PIFA Shorting Pins 43 2.3 Multisystem Techniques 45 References 52 VII
VIII Contents CHAPTER 3 Multiband Planar Wire Antennas 53 3.1 Introduction 53 3.2 Multiband Planar Monopole Antennas 59 3.2.1 Microstrip-Fed Dual-Band Monopole Antenna 60 3.2.2 CPW-Fed Dual-Band Monopole Antenna 60 3.2.3 Meandered CPW-Fed Multiband Monopole Antenna 62 3.3 Inverted-L Multiband Antennas 63 3.3.1 Modified Double Inverted-L Antenna for Multiband Operation 63 3.3.2 Inverted-L Antenna with a Parasitic Element for Dual-Band Operation 67 3.4 Inverted-F Antennas for Dual-Band Operation 68 3.4.1 Spiraled Inverted-F Antenna for Dual-Band Operation 68 3.4.2 Coupling Dual-Band Inverted-F Antenna 71 3.4.3 Inverted-FL Antennas with a Parasitic Inverted-L Element for Bandwidth Enhancement 74 3.5 T-Shaped Antennas for Multiband Operation 75 3.5.1 Single T-Shaped Antenna for Multiband Operation 75 3.5.2 Double T-Shaped Antenna for Dual-Band Operation 77 3.5.3 T-Shaped Antenna with a Parasitic Inverted-L Element for Bandwidth Improvement 78 3.6 Meandered Multiband Antennas 79 3.6.1 A Nonuniform Meandered Antenna with a Forked Ground Plane for Multiband Operation 80 3.6.2 A Compact Multiband Meandered Planar Antenna 82 3.7 M-Shaped Planar Monopole for Multiband Operation 83 3.8 Two-Strip Planar Antennas for Broadband and Multiband Operation 85 3.8.1 Broadband Two-Strip Antenna 85 3.8.2 Broadband/Dual-Frequency Two-Strip Antenna 89 3.9 Conclusions 92 References 93 CHAPTER 4 Printed Multiband Fractal Antennas 95 4.1 Introduction 95 4.1.1 Brief Background on Fractal Geometry 95 4.1.2 Fractals in Nature 97 4.1.3 Prefractals: Truncating a Fractal to Useable Complexity 99 АЛА How Fractals Can Be Used as Antennas and Why Fractals Are Space-Filling Geometries 100 4.1.5 The Fractal Dimensions of Box Counting, Hausdorff, and Similarity 101 4.2 Fractals Defined by Transformations Self-Similar and Self-Affine Sets 109 4.2.1 Iterated Function Schemes: The Language of Fractals 109 4.2.2 Self-Affine Sets 112
Contents IX 4.3 Deterministic Fractals as Antennas 113 4.3.1 Fractals as Wire Antenna Elements 114 4.3.2 Fractal Patch Elements 125 4.3.3 Circularly Polarized Microstrip Fractal Antennas 138 4.4 Fractal Arrays and Fractal Volume Antennas 141 4.4.1 Multiband Fractal Arrays 143 4.5 Conclusions 147 References 147 CHAPTER 5 Miniaturized Integrated Multiband Antennas 151 5.1 Design Considerations for Integrated Multiband Handset Antennas 151 5.1.1 Hearing Aid Compatible Handsets 152 5.2 Effect of the Terminal on the Antenna Behavior 153 5.2.1 Effect of the Size of the Chassis 153 5.2.2 Effect of the Handset Components 157 5.3 Modal Analysis 164 5.3.1 The Theory of Characteristic Modes 165 5.3.2 Practical Applications 172 Acknowledgments 182 References 229 CHAPTER 6 Multiband Handset Antennas for MIMO Systems 187 6.1 Introduction 187 6.2 Design Considerations for MIMO Systems 188 6.2.1 Diversity Techniques 190 6.2.2 Volume Constraints: The MIMO Cube 198 6.3 MIMO Techniques in a Handset 198 6.3.1 Effect of Antenna Efficiency 199 6.3.2 Effect of User Presence 212 6.3.3 Effect of Antenna Correlation 219 6.4 Combined Diversity Techniques for Optimum Handset MIMO Performance 223 CHAPTER 7 Communication Performance of Mobile Devices 235 7.1 Introduction 235 7.2 Antenna Efficiency 241 7.2.1 Radiation Efficiency 242 7.2.2 How to Obtain the Antenna Efficiency 242 7.2.3 Conductive Cable Problem 243 7.2.4 Total Radiated Power and Total Isotropic Sensitivity 246 7.3 User Influence 247
X Contents 7.3.1 Experimental Setup 248 7.3.2 Repeatability Test 251 7.3.3 Variation Due to Different Users 252 7.3.4 Influence of Hand Position 254 7.3.5 Summary 257 7.4 Mean Effective Gain 258 7.4.1 Power Distribution Models 260 7.4.2 Single Antenna 266 7.4.3 Multiple Antennas 274 7.5 Standard Measurement Setup Using Phantoms 281 7.5.1 Setup for Measurements of Mobile Handset Radiation Patterns 282 7.5.2 Measurement Uncertainty 284 7.5.3 Errors Due to Insufficient Sampling Density of Radiation Pattern 284 7.5.4 Investigation of Phantom Type Influence on Performance 285 7.5.5 Uncertainty Due to Incorrect Handset Positioning on Phantom 288 References 292 List of Acronyms 295 About the Editor 299 About the Authors 301 Index 307