Antennas for Portable Devices

Zhi Ning Chen is Lead Scientist, Head for Antenna Lab and Manager for Radio Systems Department, Institute for Infocomm Research, Singapore. Zhi Ning has been working on applied electromagnetics, antennas and RF systems for 20 years. Recently, his major research interests include wave propagation, antennas, and RF design for UWB-(Ultra WideBand) and MIMO- (multiple input, multiple output) based radio systems. He has conducted research work on UWB, including the study of small and broadband antennas for UWB radio systems, measurements on pulsed antennas UWB, assessment of diversity performance of multiple antennas in UWB systems, effects of the human body on the UWB signal propagation, co-design of antennas and RF circuits for UWB transceivers. He has been invited to give talks on UWB antenna design and measurement at several international conferences and workshops, and has organized many international UWB events.

• Foreword ixAcknowledgements xiList of Contributors xiii1 Introduction 1Zhi Ning ChenReferences 72 Handset Antennas 9Brian S. Collins2.1 Introduction 92.2 Performance Requirements 112.3 Electrically Small Antennas 142.4 Classes of Handset Antennas 182.5 The Quest for Efficiency and Extended Bandwidth 202.5.1 Handset Geometries 212.5.2 Antenna Position in the Handset 212.5.3 The Effect of the User 232.5.4 Antenna Volume 242.5.5 Impedance Behavior of a Typical Antenna in the Low Band 242.5.6 Fields and Currents on Handsets 272.5.7 Managing the Length–Bandwidth Relationship 292.5.8 The Effect on RF Efficiency of Other Components of the Handset 352.5.9 Specific Absorption Rate 382.5.10 Hearing Aid Compliance 392.5.11 Economic Considerations 392.6 Practical Design 402.6.1 Simulations 402.6.2 Materials and Construction 412.6.3 Recycling 412.6.4 Building the Prototype 412.6.5 Measurement 422.6.6 Design Optimization 442.7 Starting Points for Design and Optimization 442.7.1 External Antennas 452.7.2 Balanced Antennas 472.7.3 Antennas for Other Services 482.7.4 Dual-Antenna Interference Cancellation 492.7.5 Multiple Input, Multiple Output 492.7.6 Antennas for Lower-Frequency Bands – TV and Radio Services 502.8 The RF Performance of Typical Handsets 522.9 Conclusion 55References 553 RFID Tag Antennas 59Xianming Qing and Zhi Ning Chen3.1 Introduction 593.2 RFID Fundamentals 603.2.1 RFID System Configuration 603.2.2 Classification of RFID Systems 623.2.3 Principles of Operation 653.2.4 Frequencies, Regulations and Standardization 673.3 Design Considerations for RFID Tag Antennas 713.3.1 Near-field RFID Tag Antennas 733.3.2 Far-field RFID Tag Antennas 803.4 Effect of Environment on RFID Tag Antennas 973.4.1 Near-field Tags 983.4.2 Far-field Tags 1003.4.3 Case Study 1063.5 Summary 109References 1094 Laptop Antenna Design and Evaluation 113Duixian Liu and Brian Gaucher4.1 Introduction 1134.2 Laptop-Related Antenna Issues 1144.2.1 Typical Laptop Display Construction 1144.2.2 Possible Antennas for Laptop Applications 1154.2.3 Mechanical and Industrial Design Restrictions 1164.2.4 LCD Surface Treatment in Simulations 1184.2.5 Antenna Orientation in Display 1194.2.6 The Difference between Laptop and Cellphone Antennas 1204.2.7 Antenna Location Evaluations 1224.3 Antenna Design Methodology 1244.3.1 Modeling 1254.3.2 Cut-and-Try 1254.3.3 Measurements 1254.4 PC Card Antenna Performance and Evaluation 1274.5 Link Budget Model 1294.6 An INF Antenna Implementation 1314.7 Integrated and PC Card Solutions Comparison 1334.8 Dualband Examples 1344.8.1 An Inverted-F Antenna with Coupled Elements 1354.8.2 A Dualband PCB Antenna with Coupled Floating Elements 1384.8.3 A Loop Related Dualband Antenna 1424.9 Remarks on WLAN Antenna Design and Evaluations 1484.10 Antennas for Wireless Wide Area Network Applications 1484.10.1 INF Antenna Height Effects on Bandwidth 1494.10.2 A WWAN Dualband Example 1524.11 Ultra-Wide Band Antennas 1574.11.1 Description of the UWB Antenna 1594.11.2 UWB Antenna Measurement Results 163References 1645 Antenna Issues in Microwave Thermal Therapies 169Koichi Ito and Kazuyuki Saito5.1 Microwave Thermal Therapies 1695.1.1 Introduction 1695.1.2 Classification by Therapeutic Temperature 1695.1.3 Heating Schemes 1705.2 Interstitial Microwave Hyperthermia 1715.2.1 Introduction and Requirements 1715.2.2 Coaxial-Slot Antenna 1735.2.3 Numerical Calculation 1735.2.4 Performance of the Coaxial-Slot Antenna 1775.2.5 Temperature Distributions Around the Antennas 1805.3 Clinical Trials 1835.3.1 Equipment 1835.3.2 Treatment by Use of a Single Antenna 1835.3.3 Treatment by Use of an Array Applicator 1855.3.4 Results of the Treatment 1875.4 Other Applications 1895.4.1 Treatment of Brain Tumors 1895.4.2 Intracavitary Microwave Hyperthermia for Bile Duct Carcinoma 1895.5 Summary 194References 1956 Antennas for Wearable Devices 197Akram Alomainy, Yang Hao and Frank Pasveer6.1 Introduction 1976.1.1 Wireless Body Area Networks 1986.1.2 Antenna Design Requirements for Wireless BAN/PAN 1996.2 Modelling and Characterization of Wearable Antennas 2046.2.1 Wearable Antennas for BANs/PANs 2046.2.2 UWB Wearable Antennas 2096.3 WBAN Radio Channel Characterization and Effect of Wearable Antennas 2136.3.1 Radio Propagation Measurement for WBANs 2146.3.2 Propagation Channel Characteristics 2146.4 Case Study: A Compact Wearable Antenna for Healthcare Sensors 2186.4.1 Application Requirements 2186.4.2 Theoretical Antenna Considerations 2186.4.3 Sensor Antenna Modelling and Characterization 2206.4.4 Propagation Channel Characterization 2236.5 Summary 226References 2277 Antennas for UWB Applications 231Zhi Ning Chen and Terence S.P. See7.1 UWB Wireless Systems 2317.2 Challenges in UWB Antenna Design 2337.3 State-of-the-Art Solutions 2477.3.1 Frequency-Independent Designs 2477.3.2 Planar Broadband Designs 2487.3.3 Crossed and Rolled Planar Broadband Designs 2537.3.4 Planar Printed PCB Designs 2547.3.5 Planar Antipodal Vivaldi Designs 2577.4 Case Study 2587.4.1 Small Printed Antenna with Reduced Ground-Plane Effect 2587.4.2 Wireless USB 2707.5 Summary 282References 283Index 287

"…a fun read and offers a great look into the world of antennas in the wireless devices that surround us more and more." (IEEE Microwave Magazine, October 2007)