The increasing demand for wireless communications has
revolutionised the lifestyle of today's society and one of
the key components of wireless technology is antenna design.
Broadband planar antennas are the newest generation of antennas
boasting the attractive features required, such as broad operating
bandwidth, low profile, light weight, low cost and ease of
integration into arrays or Radio Frequency (RF) circuits, to make
them ideal components of modern communications systems. Research
into small and broadband antennas has been spurred by the rapid
development of portable wireless communication devices such as cell
phones, laptops and personal digital assistants.

This all-encompassing volume, Broadband Planar Antennas:
Design and Applications, systematically describes the
techniques for all planar antennas from microstrip patch antennas,
suspended plate antennas and planar inverted-L/F antennas to planar
dipole antennas. Also discussed are some of the most recent
outcomes such as broadband antenna issues in promising
ultra-wideband applications.

* Clearly describes the fundamentals of planar antennas and
categorises them according to their radiation characteristics

* Introduces the advanced progress in broadband planar antennas
for modern wireless communications

* Includes a wealth of case studies, design guidelines, figures
and tables

This text is essential reading for antenna, RF and microwave
engineers and manufacturers within the telecommunications industry.
Its highly accessible approach will also appeal to researchers,
postgraduate students and academic lecturers.

Dr Zhi Ning Chen is the Radio Systems Department Manager at the Institute for Infocomm Research in Singapore and is concurrently teaching at the National University of Singapore. Dr Chen has extensive R&D and teaching experience in wireless communications, electromagnetic applications, antennas and propagation. His current research interests are in antennas for cellular systems, WLANs, portable terminals and UWB radio systems.

Dr Michael Chia, is the Division Director for Communications and Devices at the Institute for Infocomm Research in Singapore, which specialises in the R&D of novel radio technology for wireless communications. Dr Chia was a member in the Panel of Public Service Funding-PSF of the Agency for Science, Technology & Research and has been listed in Marquis Who's Who in Science and Engineering.

This all-encompassing volume, Broadband Planar Antennas: Design and Applications, systematically describes the techniques for all planar antennas from microstrip patch antennas, suspended plate antennas and planar inverted-L/F antennas to planar dipole antennas. Also discussed are some of the most recent outcomes such as broadband antenna issues in promising ultra-wideband applications.

• Clearly describes the fundamentals of planar antennas and categorises them according to their radiation characteristics
• Introduces the advanced progress in broadband planar antennas for modern wireless communications
• Includes a wealth of case studies, design guidelines, figures and tables

This text is essential reading for antenna, RF and microwave engineers and manufacturers within the telecommunications industry. Its highly accessible approach will also appeal to researchers, postgraduate students and academic lecturers.

Foreword ix

Preface xi

Acknowledgements xiii

1 Planar Radiators 1

1.1 Introduction 1

1.2 Bandwidth Definitions 2

1.2.1 Impedance Bandwidth 3

1.2.2 Pattern Bandwidth 3

1.2.3 Polarization or Axial-ratio Bandwidth 4

1.2.4 Summary 5

1.3 Planar Antennas 5

1.3.1 Suspended Plate Antennas 5

1.3.2 Bent Plate Antennas 10

1.4 Overview of this Book 14

References 15

2 Broadband Microstrip Patch Antennas 17

2.1 Introduction 17

2.2 Important Features of Microstrip Patch Antennas 20

2.2.1 Patch Shapes 20

2.2.2 Substrates 20

2.2.3 Feeding Structures 21

2.2.4 Example: Rectangular Microstrip Patch Antennas 23

2.3 Broadband Techniques 31

2.3.1 Lowering the Q 31

2.3.2 Using an Impedance Matching Network 32

2.3.3 Case Study: Microstrip Patch Antenna with Impedance Matching Stub 34

2.3.4 Introducing Multiple Resonances 37

2.3.5 Case Study: Microstrip Patch Antenna with Stacked Elements 39

References 43

3 Broadband Suspended Plate Antennas 47

3.1 Introduction 47

3.2 Techniques to Broaden Impedance Bandwidth 49

3.2.1 Capacitive Load 49

3.2.2 Slotted Plates 51

3.2.3 Case Study: SPA with an -shaped Slot 52

3.2.4 Electromagnetic Coupling 56

3.2.5 Nonplanar Plates 59

3.2.6 Vertical Feed Sheet 62

3.3 Techniques to Enhance Radiation Performance 65

3.3.1 Radiation Characteristics of SPAs 66

3.3.2 SPA with Dual Feed Probes 72

3.3.3 Case Study: Center-concaved SPA with Dual Feed Probes 75

3.3.4 SPA with Half-wavelength Probe-fed Strip 77

3.3.5 SPA with Probe-fed Center Slot 81

3.3.6 Case Study: Center-fed SPA with Double L-shaped Probes 92

3.3.7 SPA with Slots and Shorting Strips 100

3.4 Arrays with Suspended Plate Elements 111

3.4.1 Mutual Coupling between Two Suspended Plate Elements 112

3.4.2 Reduced-size Array above Double-tiered Ground Plane 117

References 131

4 Planar Inverted-L/F Antennas 135

4.1 Introduction 135

4.2 The Inverted-L/F Antenna 137

4.3 Broadband Planar Inverted-F/L Antenna 141

4.3.1 Planar Inverted-F Antenna 141

4.3.2 Planar Inverted-L Antenna 144

4.4 Case Studies 154

4.4.1 Handset Antennas 154

4.4.2 Laptop Computer Antennas 171

References 174

5 Planar Monopole Antennas and Ultra-wideband Applications 179

5.1 Introduction 179

5.2 Planar Monopole Antenna 181

5.2.1 Planar Bi-conical Structure 181

5.2.2 Planar Monopoles 181

5.2.3 Roll Monopoles 183

5.2.4 EMC Feeding Methods 192

5.3 Planar Antennas for UWB Applications 193

5.3.1 Ultra-wideband Technology 193

5.3.2 Considerations for UWB Antennas and Source Pulses 195

5.3.3 Planar UWB Antenna and Assessment 212

5.4 Case Studies 218

5.4.1 Planar UWB Antenna Printed on a PCB 220

5.4.2 Planar UWB Antenna Embedded into a Laptop Computer 227

5.4.3 Planar Directional UWB Antenna 232

References 237

Index 241