Contents
Acronyms i
Contributors i
1 Introduction 1
1.1. Why This Book? 1
1.2. Why Focus on mm-Wave Antennas? 2
1.3. Intended Audience 2
1.4. What This Book Covers 3
1.5. Scope and Limitations 4
1.6. Concluding Remarks 4
1.7. Organization and Flow of the Book 5
Bibliography 6
2 Millimeter-Wave Wireless Communication Systems 1
2.1. Understanding the RF Spectrum: From Low Frequencies to Terahertz
3
2.1.1. Very Low to High Frequencies (3 kHz - 30 MHz) 3
2.1.2. VHF and UHF Bands (30 MHz - 3 GHz) 4
2.1.3. Microwave Region (3 GHz - 30 GHz) 4
2.1.4. Millimeter-Wave (30 GHz - 300 GHz) 4
2.1.5. Terahertz (THz) Band (300 GHz - 3 THz) 4
2.2. Applications of mm-wave Frequencies 5
2.2.1. 5G and Beyond Mobile Networks 5
2.2.2. High-Speed Indoor Wireless Networks 6
2.2.3. Automotive and V2X Communications 6
2.2.4. Wireless Backhaul and Fronthaul 6
2.2.5. Healthcare and Medical Imaging 7
2.2.6. Industrial Automation and Smart Factories 7
2.2.7. Immersive Technologies: AR, VR, and XR 7
2.2.8. Security Screening and Surveillance 8
2.3. Impairments in Millimeter-Wave Antennas and Communication
Systems 8
2.3.1. High Free-Space Path Loss 8
2.3.2. Poor Penetration Through Obstacles 9
2.3.3. Sensitivity to Line-of-Sight and Blockages 10
2.3.4. Rain, Fog, and Atmospheric Absorption 10
2.3.5. Challenges in Antenna and Circuit Design 11
2.3.6. Beamforming and Mobility Limitations 11
2.3.7. Thermal and Noise Issues 11
2.4. Design Strategies for Millimeter-Wave Antennas 12
2.4.1. Material Considerations 12
2.4.2. Size and Miniaturization 13
2.4.3. Feeding Techniques 13
2.4.4. Impedance Matching and Bandwidth Enhancement 14
2.4.5. Array Design and Beam Steering 14
2.4.6. Integration with Packaging 14
2.4.7. Simulation and Fabrication Constraints 14
2.5. Fabrication and Measurement Techniques for Millimeter-Wave
Antennas 15
2.5.1. Fabrication Techniques 15
2.5.2. Measurement Techniques 17
2.5.3. Challenges and Best Practices 18
2.6. Conclusion 19
Bibliography 20
3 Millimeter-Wave Planar Antennas 1
3.1. Introduction 1
3.1.1. Why Planar Antennas for mm-Wave? 2
3.1.2. Design Considerations and Challenges 2
3.1.3. Applications of Planar mm-Wave Antennas 4
3.2. Microstrip Antennas 4
3.2.1. Basic Structure and Operation 4
3.2.2. Advantages at mm-Wave Frequencies 6
3.2.3. Design Considerations and Challenges 6
3.2.4. Applications 6
3.2.5. Design Example 7
3.3. Aperture-Coupled Antennas 10
3.3.1. Structure and Principle of Operation 10
3.3.2. Advantages for mm-Wave Design 11
3.3.3. Design Challenges 11
3.3.4. Applications 11
3.4. Substrate Integrated Waveguide (SIW) Antennas 12
3.4.1. What is SIW? 12
3.4.2. Why SIW is Great for mm-Wave? 12
3.4.3. SIW Antenna Types 13
3.4.4. Design Considerations 13
3.4.5. Applications of SIW Antennas 14
3.4.6. Design Example 14
3.5. Millimeter-Wave Slot Antennas 16
3.5.1. Principle of Operation 18
3.5.2. Slot Width and Bandwidth Considerations 19
3.5.3. Feeding Mechanisms 19
3.5.4. Applications and Advantages 19
3.5.5. Design Note for Arrays 20
Conclusion 20
Bibliography 20
4 Millimeter-Wave Dielectric Resonator Antennas 1
4.1. Introduction 1
4.2. Dielectric Resonator Antennas 1
4.3. Advantages of DRAs at mm-Wave Frequencies 2
4.4. Dielectric Materials for Dielectric Resonator Antennas 4
4.5. Conductor and Dielectric Losses 6
4.6. Feeding Techniques 7
4.6.1. Coaxial Probe Feeding Technique 8
4.6.2. Electromagnetically Coupled Dielectric Resonator Antennas
8
4.6.3. Aperture-Coupled Dielectric Resonator Antennas 10
4.6.4. Coplanar Waveguide-Fed Dielectric Resonator Antennas 11
4.7. Applications of Dielectric Resonator Antennas 12
4.7.1. Wireless Communication Systems 12
4.7.2. Automotive Radar Systems 12
4.7.3. Wireless Sensing and Imaging 13
4.7.4. Satellite and Point-to-Point Links 13
4.7.5. Research and Experimental Use 14
4.8. Conclusion 14
Bibliography 14
5 Substrate Integrated Waveguide Based mm-wave Antennas 1
5.1. Introduction 1
5.2. Single-Band SIW Antennas 3
5.2.1. Waveguide Dimensions and Effective Width 3
5.2.2. Rules for Via Placement 4
5.2.3. Cavity-Type Single-Band SIW Antenna 5
5.2.4. Radiation and Bandwidth Considerations 6
5.2.5. Summary of Design Process 6
5.3. Multi-Band SIW Antennas 7
5.3.1. Concept of Multi-Band Operation 7
5.3.2. Self-Diplexing SIW Antennas 7
5.3.3. Self-Triplexing SIW Antennas 8
5.3.4. Self-Quadruplexing SIW Antennas 10
5.3.5. Placement of Vias and Multi-Band Stability 10
5.3.6. Feed Structures and Isolation Between Bands 11
5.3.7. Advantages and Application Context 11
5.4. SIW Antennas Arrays 11
5.4.1. Array Configurations 13
5.4.2. Beam Steering and Pattern Control 13
5.4.3. Mutual Coupling Considerations 14
5.4.4. Performance at mm-Wave Frequencies 14
5.5. Wideband SIW Antennas 14
5.6. Conclusion 15
Bibliography 16
6 Wideband Millimeter-wave Antennas 1
6.1. Why Wideband Antennas? 1
6.2. Bandwidth Enhancement Techniques 3
6.3. Stacked Microstrip Antenna Techniques for Bandwidth Enhancement
4
6.3.1. Basic Structure and Bandwidth Problem 4
6.3.2. Principle of Bandwidth Enhancement 5
6.3.3. Coupling Distance and Material Effects 6
6.3.4. Feeding Techniques 6
6.3.5. Mechanical and Manufacturing Considerations 6
6.4. Parasitic-Element Techniques for Bandwidth Enhancement 7
6.4.1. Basic Idea of Parasitic Elements 7
6.4.2. Spacing Between Radiator and Parasitic Element 8
6.4.3. Different Parasitic-Element Positions 8
6.4.4. Directors and Reflectors 9
6.4.5. Multiple Parasitic Elements 9
6.4.6. Printed Parasitic Structures 9
6.4.7. Aperture-Type Parasitic Elements 10
6.4.8. Bandwidth and Gain Trade-Off 10
6.4.9. Benefits for mm-Wave Systems 11
6.4.10. Practical Design Challenges 11
6.5. Hybrid Techniques 12
6.5.1. Mix of Slot and Patch Antennas 13
6.5.2. Mix of Stacked Layers and Parasitic Elements 13
6.5.3. Mix of Different Feeds and Radiators 14
6.5.4. Mix of Slots and Parasitic Edges 14
6.5.5. Mix with Electromagnetic Band Gap (EBG) 15
6.5.6. Mix of Tuning Stubs and Modified Ground 15
6.5.7. Advantages of Hybrid Techniques 15
6.5.8. Design Challenges 15
6.5.9. Practical Examples 16
6.6. Conclusion 16
Bibliography 16
7 Millimeter-Wave Planar Antenna Arrays 1
7.1. Introduction 1
7.1.1. What is a Planar Antenna Array? 1
7.1.2. Importance of mm-Wave Planar Arrays 2
7.1.3. Design Considerations for mm-Wave Planar Arrays 4
7.1.4. Applications of Planar Arrays 6
7.1.5. Challenges in mm-Wave Planar Array Design 7
7.1.6. Summary 8
7.2. Series-Fed Antenna Arrays 8
7.2.1. Introduction 8
7.2.2. Basic Concept of Series-Fed Arrays 10
7.2.3. Array Factor of Series-Fed Arrays 10
7.2.4. Design of Series-Fed Arrays 11
7.2.5. Transmission Line Model 12
7.2.6. Radiation Pattern Analysis 12
7.2.7. Advantages of Series-Fed Arrays 12
7.2.8. Limitations 12
7.2.9. Practical Applications 13
7.2.10. Example: Series-Fed Microstrip Array 13
7.2.11. Summary 13
7.3. Parallel-Fed Arrays 13
7.3.1. Introduction 13
7.3.2. Parallel Feeding Basics 14
7.3.3. Array Factor and Radiation Pattern 15
7.3.4. Power Division and Phase Control 16
7.3.5. Types of Parallel Feeding Networks 17
7.3.6. Mutual Coupling and Losses 18
7.3.7. Applications of Parallel-Fed Arrays 18
7.3.8. Summary 18
7.4. Combination-Fed Arrays 19
7.4.1. Introduction 19
7.4.2. Principle of Combination Feeding 19
7.4.3. Need for Combination-Fed Arrays 20
7.4.4. Array Factor and Mathematical Model 20
7.4.5. Current and Phase Distribution 21
7.4.6. Typical Combination Structures 21
7.4.7. Design Considerations and Equations 22
7.4.8. Beam Steering and Pattern Control 22
7.4.9. Loss, Bandwidth, and Efficiency 23
7.4.10. Mutual Coupling and Matching 23
7.4.11. Comparison with Series and Parallel Arrays 23
7.4.12. Applications 24
7.4.13. Summary 24
7.5. Design Considerations for Antenna Arrays 25
7.5.1. Element Spacing 25
7.5.2. Amplitude Distribution 25
7.5.3. Phase Control 25
7.5.4. Impedance Matching 26
7.5.5. Mutual Coupling 26
7.5.6. Feed Network Design 26
7.5.7. Bandwidth 26
7.5.8. Physical and Fabrication Constraints 26
7.6. Conclusion 27
Bibliography 27
8 Millimeter-wave Reconfigurable Antennas Using FSS 1
8.1. Introduction 1
8.1.1. Challenges of Antenna Design at mm-wave Frequencies 2
8.1.2. Why Reconfigurable Antennas 2
8.1.3. Role of Frequency Selective Surfaces (FSS) 3
8.1.4. Summary 4
8.2. Fundamentals of Frequency Selective Surfaces (FSS) 5
8.2.1. Definition and Basic Principle of Operation 5
8.2.2. Transmission vs. Reflection Mode FSS 6
8.2.3. Equivalent Circuit Models for FSS 7
8.2.4. Types of Unit Cells 7
8.2.5. Bandpass, Bandstop, and Polarization-dependent Designs 8
8.2.6. Summary 9
8.3. Millimeter-wave Reconfigurable Antennas 9
8.3.1. Overview of Reconfigurability 9
8.3.2. Frequency Reconfigurability 9
8.3.3. Polarization Reconfigurability 10
8.3.4. Radiation Pattern Reconfigurability 10
8.3.5. Gain and Beam Steering Reconfigurability 10
8.3.6. Techniques for Reconfiguration 11
8.3.7. Challenges at Millimeter-wave Bands 13
8.3.8. Summary 15
8.4. Integration of FSS with mm-wave Reconfigurable Antennas 15
8.4.1. FSS as Superstrate for Gain Enhancement 15
8.4.2. FSS as a Reconfigurable Reflector/Absorber for Beam Control
16
8.4.3. FSS-based Polarization Reconfigurable Antennas 16
8.4.4. FSS Metasurfaces for Multi-band and Wideband Operation
17
8.4.5. Hybrid Integration: FSS with Phased Arrays, RIS, and MIMO Antennas
17
8.4.6. Conclusion 18
8.5. Design Methodologies 18
8.5.1. Unit Cell Design and Periodicity Considerations 18
8.5.2. Simulation Approaches: CST, HFSS, and Equivalent Circuit Models
19
8.5.3. Parametric Analysis of Unit Cell Geometry and Materials 20
8.5.4. Biasing Techniques for Active FSS Elements 20
8.5.5. Fabrication Challenges: Lithography, 3D Printing, and Flexible
Substrates 21
8.5.6. Summary 21
8.6. Performance Metrics 22
8.6.1. Reflection and Transmission Coefficient (S-Parameters) 22
8.6.2. Bandwidth and Frequency Agility 22
8.6.3. Gain Enhancement and Beam Shaping 23
8.6.4. Efficiency and Losses at mm-wave 23
8.6.5. Isolation in MIMO Configurations 24
8.6.6. Trade-offs Between Complexity, Cost, and Performance 24
8.6.7. Summary 24
8.7. Applications 25
8.7.1. 5G and 6G mm-wave Wireless Communication Systems 25
8.7.2. Satellite and Space Communications 26
8.7.3. mm-wave Radar and Imaging Systems 26
8.7.4. Wireless Power Transfer and Energy Harvesting 27
8.7.5. Integration with RIS for Smart Environments 28
8.7.6. Summary 28
8.8. Challenges and Future Trends 28
8.8.1. Fabrication and Tolerance Issues at mm-wave Bands 28
8.8.2. Thermal and Power Handling Constraints of Reconfigurable FSS
29
8.8.3. Integration with CMOS and Compact Packaging 29
8.8.4. Emergence of Tunable 2D Materials for FSS-Based Reconfigurable
Antennas 30
8.8.5. AI/ML-Driven Optimization for Adaptive FSS-Based Antenna Systems
30
8.8.6. Future Perspective: Convergence of FSS, RIS, and mm-wave Antennas
for 6G and THz Systems 31
8.8.7. Summary 31
8.8.8. Summary of the Role of FSS in Enabling Reconfigurability 31
8.8.9. Potential for Next-Generation Wireless and Sensing Systems
32
8.8.10. Open Research Directions 33
8.8.11. Summary Table of Key Points 34
8.8.12. Conclusion 34
Bibliography 35
9 Orbital Angular Momentum (OAM) Antennas 1
9.1. Introduction 1
9.2. Fundamentals of OAM 3
9.2.1. Angular Momentum in Electromagnetics 3
9.2.2. Orthogonality of OAM Modes 4
9.3. OAM Generation 4
9.3.1. Spiral Phase Plates 4
9.3.2. Uniform Circular Arrays 5
9.3.3. Phased Arrays with Progressive Phase Shift 5
9.3.4. Metasurfaces 6
9.3.5. Dielectric Resonator Modes 6
9.3.6. Array Factor for OAM Modes 6
9.4. Challenges in OAM Antennas 6
9.4.1. Beam Divergence 7
9.4.2. Mode Purity and Cross-Talk 7
9.4.3. Multipath Sensitivity 8
9.4.4. Receiver Architectures 8
9.5. Applications of OAM Antennas 8
9.5.1. Point-to-Point High-Capacity Links 9
9.5.2. Secure Communications 9
9.5.3. Chip-to-Chip Wireless Links 9
9.5.4. Radar and Imaging Applications 9
9.6. Future Outlook 9
9.7. Design Example 10
9.7.1. Literature Review 10
9.7.2. Unit cell characteristics 12
9.7.3. Mixed-OAM generating TA design 14
9.7.4. Experimental verification 16
9.7.5. Discussion 17
9.7.6. Summary 20
9.8. Conclusion 20
Bibliography 20
10 Conclusion 1
