Antenna Design for Mobile Devices (eBook)

Zhijun Zhang is a Professor of Electronic Engineering at Tsinghua University in Beijing, China. He holds rich industry experience, with senior positions as an antenna development engineer at Amphenol T&M Antennas, Nokia, and Apple, giving him a perspective of design practices at a number different players in the mobile segment. Prior to Tsinghua, his academic career included a postdoctoral fellowship and research professorship at the University of Utah, and a position as Assistant Researcher at the University of Hawaii, where he continues to serve as Adjunct Professor. Zhang earned a B.S. in Microwave Engineering and an M.S. in Applied Physics at the University of Electronic Science and Technology of China, Chengdu. He holds a PhD in Electronic Engineering from Tsinghua University.

Preface xi

Acknowledgments xiii

About the Author xv

Abbreviations xvii

1 Introduction 1

1.1 The Evolution of Mobile Antennas 3

1.2 How to Quantitatively Evaluate an Antenna 8

1.3 The Limits of Antenna Designs 11

1.4 The Trade-Offs in Antenna Designs 13

1.5 Mobile Communication and Band Allocations 15

References 17

2 Antenna Matching 19

2.1 The Smith Chart 20

2.2 Single Band Matching 23

2.2.1 Matching with Lumped Elements 25

2.2.2 Different Ways to Accomplish a Single Band Matching 28

2.2.3 Matching with Both Transmission Line and Lumped Elements
31

2.2.4 Bandwidth Consideration 35

2.3 Dual Band Matching 43

2.4 Reconfigurable Matching 48

2.4.1 Reconfigurable Matching - Varactor-Based 49

2.4.2 Reconfigurable Matching - Switch-Based 52

References 57

3 External Antenna 59

3.1 Stubby Antennas 61

3.1.1 Single Band Helix Stubby Antenna 61

3.1.2 Multi-Band Helix Stubby Antenna 81

3.1.3 Ultra-Wide Band Stubby Antenna 105

3.2 Whip-Stubby (Retractable) Antenna 115

3.2.1 Decoupled Whip-Stubby Antenna 117

3.2.2 Semi-Decoupled Whip-Stubby Antenna 119

3.3 Meander Line Stubby Antenna 125

3.4 Effect of Ground Plane 129

References 136

4 Internal Antenna 139

4.1 Inverted-F Antenna (IFA) 141

4.2 Planar Inverted-F Antenna (PIFA) 147

4.2.1 Single Band PIFA 147

4.2.2 Multi-Band PIFA Antenna with Slits 150

4.2.3 Multi-Band PIFA with Separate Branches 159

4.2.4 Multi-Band PIFA with Parasitic Element 160

4.2.5 Manufacturing PIFA Antenna 161

4.3 Folded Monopole Antenna 165

4.4 Loop Antenna 170

4.5 Ceramic Antenna 175

4.5.1 Monopole-Type Ceramic Antenna 176

4.5.2 IFA-Type Ceramic Antenna 180

4.5.3 Loop-Type Ceramic Antenna 181

4.6 Multi-Port Internal Antenna Module 182

References 187

5 Antenna Measurement 189

5.1 Passive Antenna Measurement 189

5.1.1 Measurement on a Vector Network Analyzer 189

5.1.2 Fixture 195

5.1.3 Passive Chamber Measurement 207

5.2 Active Antenna (OTA) Measurement 215

5.2.1 EIRP, ERP, and TRP 216

5.2.2 EIS and TIS 220

5.2.3 Sensitivity Degradation Due to Interference 223

5.3 Antenna Measurements in the Production Line 226

References 236

6 Regulations Related to Antenna Engineers 239

6.1 Specific Absorption Rate (SAR) 239

6.1.1 Definition and Measurement Method of SAR 240

6.1.2 SAR Limits in the United States and Europe 247

6.1.3 Controlling SAR 249

6.2 Hearing Aid Compatibility (HAC) 259

6.2.1 HAC Measurement 260

6.2.2 HAC Specification in the United States 263

6.3 Electromagnetic Compatibility (EMC) 268

References 269

Appendix: User Manual for ZJ_Antenna_Matching Software 271

Index 279