Electromagnetic Band Gap Structures in Antenna Engineering

FAN YANG University of Mississippi

YAHYA RAHMAT-SAMII University of California at Los Angeles

Hfl CAMBRIDGE Щ0 UNIVERSITY PRESS

Contents

Preface Acknowledgements Abbreviations

Introduction

1.1 Background 1.2 Electromagnetic band gap (EBG) structures

1.2.1 EBG definition 1.2.2 EBG and metamaterials

1.3 Analysis methods for EBG structures 1.4 EBG applications in antenna engineering

1.4.1 Antenna substrates for surface wave suppressions 1.4.2 Antenna substrates for efficient low profile wire antenna 1.4.3 Reflection/transmission surfaces for high gain antennas

FDTD method for periodic structure analysis

2.1 FDTD fundamentals 2.1.1 Introduction 2.1.2 Yee's cell and updating scheme 2.1.3 Absorbing boundary conditions: PML 2.1.4 FDTD excitation 2.1.5 Extraction of characteristic parameters

2.2 Periodic boundary conditions 2.2.1 Fundamental challenges in PBC 2.2.2 Overview of various PBCs 2.2.3 Constant kx method for scattering analysis

2.3 Guided wave analysis 2.3.1 Problem statement 2.3.2 Brillouin zone for periodic waveguides 2.3.3 Examples

2.4 Plane wave scattering analysis 2.4.1 Problem statement 2.4.2 Plane wave excitation 2.4.3 Examples

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2.5 A unified approach: hybrid FDTD/ARMA method 45 2.5.1 A unified approach for guided wave and scattering analysis 45 2.5.2 ARMA estimator 49 2.5.3 Examples 51

2.6 Projects 54

EBG characterizations and classifications 59

3.1 Resonant circuit models for EBG structures 59 3.1.1 Effective medium model with lumped LC elements 59 3.1.2 Transmission line model for surface waves 61 3.1.3 Transmission line model for plane waves 62

3.2 Graphic representation of frequency band gap 63 3.2.1 FDTD model 63 3.2.2 Near field distributions inside and outside the frequency band

gap 65 3.3 Frequency band gap for surface wave propagation 67

3.3.1 Dispersion diagram 67 3.3.2 Surface wave band gap 68

3.4 In-phase reflection for plane wave incidence 69 3.4.1 Reflection phase 69 3.4.2 EBG reflection phase: normal incidence 70 3.4.3 EBG reflection phase: oblique incidence 71

3.5 Soft and hard surfaces 74 3.5.1 Impedance and reflection coefficient of a periodic ground plane 75 3.5.2 Soft and hard operations 77 3.5.3 Examples 80

3.6 Classifications of various EBG structures 84 3.7 Project 85

Designs and optimizations of EBG structures 87

4.1 Parametric study of a mushroom-like EBG structure 87 4.1.1 Patch width effect 87 4.1.2 Gap width effect 89 4.1.3 Substrate thickness effect 89 4.1.4 Substrate permittivity effect 90

4.2 Comparison of mushroom and uni-planar EBG designs 91 4.3 Polarization-dependent EBG surface designs 95

4.3.1 Rectangular patch EBG surface 95 4.3.2 Slot loaded EBG surface 97 4.3.3 EBG surface with offset vias 97 4.3.4 An example application: PDEBG reflector 99

4.4 Compact spiral EBG designs 103 4.4.1 Single spiral design 103

Contents vii

4.4.2 Double spiral design 105 4.4.3 Four-arm spiral design 105

4.5 Dual layer EBG designs 107 4.6 Particle swarm optimization (PSO) of EBG structures 112

4.6.1 Particle swarm optimization: a framework 112 4.6.2 Optimization for a desired frequency with a +90° reflection

phase 113 4.6.3 Optimization for a miniaturized EBG structure 117 4.6.4 General steps of EBG optimization problems using PSO 118

4.7 Advanced EBG surface designs 120 4.7.1 Space filling curve EBG designs 120 4.7.2 Multi-band EBG surface designs 120 4.7.3 Tunable EBG surface designs 120

4.8 Projects 124

Patch antennas with EBG structures 127

5.1 Patch antennas on high permittivity substrate 127 5.2 Gain enhancement of a single patch antenna 130

5.2.1 Patch antenna surrounded by EBG structures 130 5.2.2 Circularly polarized patch antenna design 132 5.2.3 Various EBG patch antenna designs 136

5.3 Mutual coupling reduction of a patch array 13 8 5.3.1 Mutual coupling between patch antennas on high dielectric

constant substrate 139 5.3.2 Mutual coupling reduction by the EBG structure 142 5.3.3 More design examples 147

5.4 EBG patch antenna applications 149 5.4.1 EBG patch antenna for high precision GPS applications 149 5.4.2 EBG patch antenna for wearable electronics 149 5.4.3 EBG patch antennas in phased arrays for scan blindness

elimination 151 5.5 Projects 153

Low profile wire antennas on EBG ground plane 156

6.1 Dipole antenna on EBG ground plane 156 6.1.1 Comparison of PEC, PMC, and EBG ground planes 156 6.1.2 Operational bandwidth selection 158 6.1.3 Parametric studies 161

6.2 Low profile antennas: wire-EBG antenna vs. patch antenna 164 6.2.1 Two types of low profile antennas 164 6.2.2 Performance comparison between wire-EBG and patch

antennas 166 6.2.3 A dual band wire-EBG antenna design 169

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6.3 Circularly polarized curl antenna on EBG ground plane 171 6.3.1 Performance of curl antennas over PEC and EBG ground planes 172 6.3.2 Parametric studies of curl antennas over the EBG surface 175 6.3.3 Experimental demonstration 178

6.4 Dipole antenna on a PDEBG ground plane for circular polarization 180 6.4.1 Radiation mechanism of CP dipole antenna 181 6.4.2 Experimental results 182

6.5 Reconflgurable bent monopole with radiation pattern diversity 185 6.5.1 Bent monopole antenna on EBG ground plane 186 6.5.2 Reconflgurable design for one-dimensional beam switch 188 6.5.3 Reconflgurable design for two-dimensional beam switch 191

6.6 Printed dipole antenna with a semi-EBG ground plane 191 6.6.1 Dipole antenna near the edge of a PEC ground plane 193 6.6.2 Enhanced performance of dipole antenna near the edge of an

EBG ground plane 194 6.6.3 Printed dipole antenna with a semi-EBG ground plane 195

6.7 Summary 200 6.8 Projects 200

Surface wave antennas 203

7.1 A grounded slab loaded with periodic patches 203 7.1.1 Comparison of two artificial ground planes 203 7.1.2 Surface waves in the grounded slab with periodic patch loading 206

7.2 Dipole-fed surface wave antennas 209 7.2.1 Performance of a low profile dipole on a patch-loaded grounded

slab 209 7.2.2 Radiation mechanism: the surface wave antenna 212 7.2.3 Effect of the finite artificial ground plane 215 7.2.4 Comparison between the surface wave antenna and vertical

monopole antenna 217 7.3 Patch-fed surface wave antennas 217

7.3.1 Comparison between a circular microstrip antenna and a patch-fed SWA 218

7.3.2 Experimental demonstration 223 7.4 Dual band surface wave antenna 223

7.4.1 Crosspatch-fed surface wave antenna 226 7.4.2 Modified crosspatch-fed surface wave antenna for dual band

operation 228 7.5 Projects 236

Appendix: EBG literature review 238 Index 261