Antennas and Propagation for Body-Centric Wireless Communications Peter S. Hall Yang Hao Editors ARTECH H O U S E BOSTON LONDON artechhouse.com
Preface CHAPTER 1 Introduction to Body-Centric Wireless Communications 1.1 What Are Body-Centric Communications Systems? 1.2 Off-Body to On-Body Communications 1.3 On-Body Communications 1.4 Medical Implants and Sensor Networks 1.5 Layout of the Book References CHAPTER 2 Electromagnetic Properties and Modeling of the Human Body 2.1 Electromagnetic Characteristics of Human Tissues 2.2 Physical Body Phantoms 2.2.1 Liquid Phantoms 2.2.2 Semisolid (Gel) or Solid (Wet) Phantoms 2.2.3 Solid (Dry) Phantoms 2.2.4 Examples of Physical Phantoms 2.3 Numerical Phantoms 2.3.1 Theoretical Phantoms 2.3.2 Voxel Phantoms 2.4 Numerical Modeling Techniques for Body-Centric Wireless Communications 2.4.1 Introduction of Numerical Techniques 2.4.2 On-Body Radio Channel Modeling References XI 1 1 5 5 6 7 8 11 11 12 14 17 17 18 20 21 21 22 22 27 34 CHAPTER 3 Antennas and Propagation for On-Body Communication at Microwave Frequencies 39 3.1 Introduction 39 3.2 On-Body Channel Measurement and Modeling 41 3.3 Antenna Design 51 3.3.1 Comparison of Antenna Types 52 3.3.2 Antenna Match and Efficiency 52 3.4 Simulation and Modeling 56
VI 3.5 Systems Modeling 60 3.6 Conclusions 62 Acknowledgments 63 References 63 CHAPTER 4 Transmission Mechanism of Wearable Devices Using the Human Body as a Transmission Channel 65 4.1 Introduction to Communications Using Circuits in Direct Contact with the Human Body 65 4.2 Numerical Analysis and Equivalent Circuit Models 68 4.2.1 Whole Body Models 68 4.2.2 Arm Models 70 4.2.3 Effective Electrode Structure 73 4.2.4 Equivalent Circuit Models 74 4.3 Experiments Using Human Phantom 76 4.3.1 Measurement of the Signal Distributions 76 4.3.2 Comparison Between Measurement and Calculation 78 4.3.3 Electric Field Distributions in and Around the Arm 82 4.3.4 Received Signal Voltage of the Receiver 83 4.4 Investigation of the Dominant Signal Transmission Path 86 4.4.1 Calculation Model 86 4.4.2 Electric Field Distributions and Received Signal Voltages 87 4.5 Conclusions 89 References 91 CHAPTER 5 Body-Centric UWB Communications 93 5.1 Overview 93 5.2 Antennas 94 5.2.1 Design and Analysis 94 5.2.2 Measurements 109 5.2.3 Concluding Remarks 111 5.3 Channel Simulation and Measurement Methodology 111 5.3.1 Simulation of the Radio Propagation in Body-Centric Communication Scenarios 111 5.3.2 Measurement of the Radio Propagation in Body-Centric Communication Scenarios 112 5.3.3 Concluding Remarks 120 5.4 Channel Characterization and Modeling 121 5.4.1 General Aspects 122 5.4.2 Personal Area Network Scenarios 124 5.4.3 Body Area Network Scenarios 129 5.4.4 Concluding Remarks 144 References 147
VII CHAPTER 6 Wearable Antennas: Advances in Design, Characterization, and Application 151 6.1 Background 151 6.2 Wearable Antennas: Critical Design Issues 153 6.3 Textile Materials 155 6.4 Effects of Substrate Materials: An Example of the Fabric GPS Antenna 156 6.4.1 Effects of Ground Plane Size Attached to the Fabric Substrate on GPS Antenna Performance 159 6.5 Effect of Various Conductive Materials of Patch Antennas: An Example of WLAN Antenna on Fleece Fabric 162 6.6 Dual Frequency Wearable Antenna Design: An Example of a U-Slot Patch 166 6.6.1 Experimental Results and Discussions: Fleece and Vellux Fabrics 169 6.7 Wearable Electromagnetic Bandgap Antenna: An Example of WLAN Antenna 171 6.7.1 Remarks on Antenna Bending 176 6.8 Wearable Antennas Near the Human Body: An Example of a WLAN Antenna 180 6.8.1 Models and Methods 180 6.8.2 Results 181 6.9 Conclusions 184 Acknowledgments 186 References 186 CHAPTER 7 Body-Sensor Networks for Space and Military Applications 189 7.1 Introduction 189 7.2 Biosensor System and Basics of Biomedical RF Telemetry 190 7.2.1 Implantable Pressure Sensor 192 7.2.2 Integrated Inductor/Antenna 192 7.2.3 External Pickup Antenna 194 7.3 Antenna Design for Body Sensors 194 7.3.1 Implantable Antennas 194 7.3.2 Antennas for External Handheld Devices 203 7.4 Space, Military, and Civilian Applications 206 7.4.1 Sensors for Space Environment 206 7.4.2 Battlefield Sensors 207 7.4.3 Sensors in Hospitals and Smart Homes 207 References 208 CHAPTER 8 Antennas and Propagation for Telemedicine and Telecare: On-Body Systems 211 8.1 Telemedicine and Telecare Applications 211 8.1.1 Physiological Signals for Patient Monitoring 213 8.1.2 Technologies for Ward-Based Systems 213
8.1.3 Technologies for Home-Based and Full-Mobility Systems 215 8.1.4 Emerging Technologies and Novel Applications 215 8.1.5 Wireless Telemedicine Link Design 216 8.2 Antennas and Human Body Interaction in Personal Telemedicine 217 8.2.1 Antenna-Body Effects (Less Than 1 GHz) 220 8.2.2 Antenna-Body Effects (Greater Than 1 GHz) 224 8.2.3 Emerging Antennas 229 8.3 System Design Issues 231 8.3.1 Channel Effects 231 8.3.2 Radio Frequency Interference 232 8.4 Conclusion 236 References 236 CHAPTER 9 Medical Implant Communication Systems 241 9.1 Introduction 241 9.1.1 Inductive Coupling 242 9.1.2 MICS Standard 243 9.1.3 2.4-GHz ISM Band 244 9.2 Lossy Dispersive Media 244 9.2.1 Matter 244 9.2.2 Material Data and Measurements 245 9.2.3 Phantoms 246 9.2.4 Skin Depth 249 9.2.5 Wave Propagation: One-Dimensional FDTD Simulations 250 9.2.6 Influence of Patient 253 9.2.7 Phantom Influence on Antenna 253 9.3 Low-Profile Antennas for Implantable Medical Devices 255 9.3.1 What Is the Antenna? 256 9.3.2 Antenna Efficiency Calculations in Matter 256 9.3.3 Electric Versus Magnetic Antennas 258 9.3.4 Implantable Antenna Designs 260 9.3.5 Dependence on Insulation Thickness 266 9.3.6 SAR 267 9.4 Conclusion 268 References 269 CHAPTER 10 Summary and Conclusions 271 10.1 Overview and Conclusions 271 10.1.1 Overview of Narrowband Systems 271 10.1.2 Overview of Wideband Systems 274 10.1.3 Overview of Applications 274 10.1.4 Conclusions 275 10.2 Future Challenges 275 10.2.1 Towards Air Interfaces and New Standards 275 10.2.2 Novel Antennas for Body-Centric Wireless Communications 276
IX 10.2.3 Medical Implant Systems 276 10.2.4 Characterization of Time-Domain Systems 277 References 277 About the Authors 279 Index 289