Microstrip and Printed

Antenna Design

Second Edition

Randy Bancroft

S SCITEC PUBLISHlNeCl SHXNeriNC.

SciTech Publishing, Inc. Raleigh, NC

www.scitechpub.com

Contents

Preface to Second Edition xi Acknowledgment xiii Chapter 1 Microstrip Antennas 1

1.1 The Origin of Microstrip Radiators 1 1.2 Microstrip Antenna Analysis Methods 4 1.3 Microstrip Antenna Advantages and Disadvantages 5 1.4 Microstrip Antenna Applications 6 References 7

Chapter 2 Rectangular Microstrip Antennas 10 2.1 The Transmission Line Model 10 2.2 The Cavity Model 19

2.2.1 The TM10 and ТМш Mode 24 2.3 Radiation Pattern and Directivity of a Linear Rectangular

Microstrip Patch Antenna 28 2.4 Quarter-Wave Rectangular Microstrip Antenna 34 2.5 j Xj Rectangular Microstrip Antenna 36 2.6 Circular Polarized Rectangular Microstrip Antenna Design 38

2.6.1 Single-Feed Circularly Polarized Rectangular Microstrip Antenna Design 38

2.6.2 Dual-Feed Circularly Polarized Rectangular Microstrip Antenna Design 49

2.6.3 Quadrature (90°) Hybrid 50 2.7 Impedance and Axial Ratio Bandwidth 52 2.8 Efficiency 54 2.9 Design of a Linearly Polarized Microstrip Antenna with

Dielectric Cover 56

vn

Vlll Contents

2.10 Design Guidelines for a Linearly Polarized Rectangular Microstrip Antenna 60

2.11 Design Guidelines for a Circularly Polarized Rectangular Microstrip Antenna 64

2.12 Electromagnetically Coupled Rectangular Microstrip Antenna 65

2.13 Ultrawide Rectangular Microstrip Antenna 67 References 70

Chapter 3 Circular Microstrip Antennas 76

3.1 Circular Microstrip Antenna Properties 76 3.2 Directivity 80 3.3 Input Resistance and Impedance Bandwidth 81

3.3.1 Gain, Radiation Pattern, and Efficiency 82

3.4 Circular Microstrip Antenna Radiation Modes 83

3.4.1 The TMn Bipolar Mode 83 3.4.2 The TMn Bipolar Mode Circular Polarized Antenna

Design 84

3.4.3 The TM2i Quadrapolar Mode 88

3.4.4 The TM02 Unipolar Mode 91 3.5 Microstrip Antenna Cross Polarization 92

3.6 Annular Microstrip Antenna 97 References 100

Chapter 4 Broadband Microstrip Antennas 102

4.1 Broadband Microstrip Antennas 102 4.2 Microstrip Antenna Broadbanding 103

4.2.1 Microstrip Antenna Matching with Capacitive Slot 105 4.2.2 Microstrip Antenna Broadband Matching with

Bandpass Filter 106 4.2.3 Microstrip Antenna Broadband Matching Using

Lumped Elements I l l 4.2.4 Lumped Elements to Transmission Line Section

Conversion 113

Contents ix

4.2.5 Real Frequency Technique Broadband Matching 119 4.2.6 Matching Network Optimization Using Genetic

Algorithms 119

4.3 Patch Shape for Optimized Bandwidth 120

4.3.1 Patch Shape Bandwidth Optimization Using Genetic

Algorithms 121 References 123

Chapter 5 Dual-Band Microstrip Antennas 126

5.0 Dual-Band Microstrip Antennas 126 5.1 Single-Resonator Rectangular Microstrip Dual-Band

Antenna 126

5.2 Multiple Resonator Dual-Band Antennas 131 5.2.1 Coupled Microstrip Dipoles 131 5.2.2 Stacked Rectangular Microstrip Antennas 131

5.3 Dual-Band Microstrip Antenna Design Using a Diplexer 134 5.3.1 Example Dual-Band Microstrip Antenna Design

Using a Diplexer 137

5.4 Multiband Microstrip Design Using Patch Shaping and a

Genetic Algorithm 140

References 141

Chapter 6 Microstrip Arrays 142

6.0 Microstrip Arrays 142 6.1 Planar Array Theory 142 6.2 Rectangular Microstrip Antenna Array Modeled Using Slots 146

6.3 Aperture Excitation Distribution 148

6.4 Microstrip Array Feeding Methods 154 6.4.1 Corporate Fed Array 154

6.4.2 Series Fed Array 157 6.5 Phase and Amplitude Error 163 6.6 Mutual Coupling 165

6.6.1 Mutual Coupling Between Square Microstrip Antennas . . . . 170

References 176

X Contents

Chapter 7 Printed Antennas 178 7.0 Printed Antennas 178 7.1 Omnidirectional Microstrip Antenna 178

7.1.1 Low Sidelobe Omnidirectional Microstrip Antenna 186 7.1.2 Element Shaping of Omnidirectional Microstrip

Antenna 188 7.1.3 Single-Short Omnidirectional Microstrip Antenna 191

7.2 Stripline Fed Tapered Slot Antenna 192 7.2.1 Stripline Fed Vivaldi Antenna 197

7.3 Meanderline Antenna 199

7.3.1 Electrically Small Antennas 199 7.3.2 Meanderline Antenna Design 203

7.3.2.1 MeanderUne Antenna Impedance Bandwidth 203 7.3.2.2 Meanderline Antenna Radiation Patterns 207

7.4 Half-Patch with Reduced Short Circuit Plane 211 7.4.1 Dual-Band PIFA 217

7.5 Rectangular Microstrip Fed Slot Antenna 219

7.5.1 Slot Antenna "Fictitious Resonance" 222 7.6 Microstrip Fed Log Periodic Balun Printed Dipole 225 7.7 Microstrip Fed Tapered Balun Printed Dipole 228

References 232

Appendix A: Microstrip Antenna Substrates 235

Appendix B: Numerical Methods 243 Appendix C: Microstrip Transmission Line Design

and Discontinuities 249

Appendix D: Antenna Topics 257 Appendix E: Impedance Matching Techniques 268

Index 284