Low-cost Smart Antennas

Preface ix Acknowledgement xi List of Abbreviations xiii 1 Introduction to Smart Antennas 1 1.1 Introduction 1 1.2 Antenna Fundamentals 2 1.2.1 Antenna Impedance and Bandwidth 2 1.2.2 Radiation Patterns and Efficiency 4 1.2.3 Polarisations 8 1.3 Antenna Array Fundamentals 9 1.3.1 Array Performance Analysis 12 1.3.2 Active Reflection Coefficient and Mutual Coupling 12 1.3.3 Directivity and Beamwidth 14 1.3.4 Grating Lobe 15 1.3.5 Scan Blindness 16 1.4 Smart Antenna Architecture and Hardware Implementation 17 1.4.1 ADC and DAC 20 1.4.2 Digital Down-Converter (DDC) 20 1.4.3 Digital Signal Processor 20 1.4.4 Field-programmable Gate Array 21 1.5 Overview of the Book 22 References 23 2 Beamforming Algorithms for Smart Antennas 25 2.1 Introduction 25 2.2 Basic Concepts for Beamforming 27 2.3 Fixed Beamformer Design 30 2.3.1 FIR Filter Based Design 30 2.3.2 Least Squares Based Design 32 2.3.3 Beam Steering 33 2.4 Adaptive Beamforming Algorithms 36 2.4.1 Reference Signal Based Beamformer 36 2.4.2 The Capon Beamformer 38 2.5 Blind Beamforming Algorithms 40 2.5.1 The Power Minimisation Algorithm 40 2.5.2 The Constant Modulus Algorithm 42 2.6 Low-cost Adaptive Beamforming 43 2.6.1 Analogue and Digital Hybrid Beamforming 43 2.6.2 Robust Adaptive Beamforming 45 2.7 Summary of the Chapter 50 References 50 3 Electronically Steerable Parasitic Array 59 3.1 Introduction 59 3.2 Theory and Operation Principle 59 3.3 Low-cost Folded-monopole ESPAR 63 3.4 ESPAR Antenna with Low Control Voltage 70 3.4.1 FM-ESPAR using PIN diodes 70 3.4.2 Link Quality Test 72 3.5 Planar ESPAR Antennas 75 3.6 Case Studies 86 3.6.1 ESPAR using Monopole 86 3.6.2 Planar Ultra-thin ESPAR 90 3.7 Summary of the Chapter 98 References 99 4 Beam-Reconfigurable Antennas Using Active Frequency Selective Surfaces 103 4.1 Introduction 103 4.2 FSS Fundamentals and Active FSSs 104 4.2.1 FSS Elements 104 4.2.2 Dielectric Loading Effects 105 4.2.3 FSS Analysis Techniques 106 4.2.4 Active Metal Strip FSS 107 4.2.5 Active Slot FSS 111 4.2.6 Active FSS Biasing Techniques 113 4.3 Monopole-fed Beam-switching Antenna using AFSS 114 4.4 Dual-Band Beam-Switching Antenna using AFSS 120 4.5 3D Beam Coverage of Electronic Beam-Switching Antenna using FSS 125 4.6 Frequency-agile Beam-switchable Antenna 138 4.7 Continuous Beam-steering Antennas using FSSs 145 4.8 Case Study 153 4.9 Summary of the Chapter 159 References 160 5 Beam Reconfigurable Reflectarrays and Transmitarrays 165 5.1 Introduction 165 5.2 Reflectarray and Transmitarray Design Fundamentals 166 5.2.1 Reflectarrays 166 5.2.2 Transmitarrays 169 5.3 Beam Reconfigurable Reflectarrays 171 5.3.1 Multi-feed Reflectarray 171 5.3.2 Reflectarray with RF Switches 174 5.3.3 Reflectarray with Tunable Components 177 5.4 Beam Reconfigurable Transmitarray 181 5.5 Circularly Polarised Beam-steerable Reflectarrays and Transmitarrays 185 5.6 Case Study 189 5.7 Summary of the Chapter 195 References 196 6 Compact MIMO Antenna Systems 199 6.1 Introduction 199 6.2 MIMO Antennas 199 6.2.1 Isolation 200 6.2.2 Envelope Correlation Coefficient 201 6.2.3 Total Active Reflection Coefficient 202 6.3 Compact MIMO Antenna with High Isolation 203 6.3.1 Neutralisation Technique 203 6.3.2 Metamaterial 205 6.3.3 Decoupling Network 209 6.4 Compact MIMO Antenna with Adaptive Radiation Patterns 215 6.5 Case Studies 218 6.5.1 Increase the Physical Separation 220 6.5.2 Change the Antenna Orientation 220 6.5.3 Modify the Ground Plane 222 6.5.4 Summary 224 6.6 Summary of the Chapter 225 References 225 7 Other Types of Low-cost Smart Antennas 229 7.1 Introduction 229 7.2 Lens Antennas 229 7.2.1 Lens Antenna Basics 229 7.2.2 Millimetre-wave Lens Antenna Design 231 7.3 Retrodirective Array Antenna 236 7.3.1 Van Altta Array 237 7.3.2 Phase Conjugating Array 239 7.4 Fabry-Perot Resonator Antennas 243 7.5 Array-fed Reflector 246 7.5.1 Operation Principle 246 7.5.2 Beam-switching Performance 251 7.6 Multibeam Antennas based on BFN 253 7.6.1 Butler Matrix 253 7.6.2 Rotman Lens 257 7.6.3 Blass and Nolen matrices 259 7.7 Summary of the Chapter 261 References 262 Index 267

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• Engenharia electrónica