JOHN THORNTON, PhD, has held research posts at the University of Oxford and the University of York. In 2010, he joined MDA Space and Robotics Ltd to lead their UK antennas program. He has published a number of technical papers, reports, and patent applications, many in the field of antenna engineering.KAO-CHENG HUANG, PhD, is a Fellow of the Institution of Engineering and Technology (IET) UK, Vice President at the Dharma Academy, and President of the Association of Vijnaptimatrata of China in Taiwan. Dr. Huang is the author of two previous books, including Millimeter Wave Communication Systems (Wiley-IEEE Press), and holds several patents in the area of millimeter wave antennas.

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• Preface ix Acknowledgments xi1 INTRODUCTION 1John Thornton and Kao-Cheng Huang1.1 Lens Antennas: An Overview 21.1.1 The Microwave Lens 21.1.2 Advantages of Lens Antennas 41.1.3 Materials for Lenses 51.1.4 Synthesis 61.2 Feeds for Lens Antennas 81.2.1 Microstrip Feeds 81.2.2 Horn Feeds 91.3 Luneburg and Spherical Lenses 101.4 Quasi Optics and Lens Antennas 141.5 Lens Antenna Design 181.6 Metamaterial Lens 261.7 Planar Lens or Phase-Shifting Surface 301.7.1 Refl ect Array 311.7.2 Planar Lens or Lens Array 331.8 Applications 361.9 Antenna Measurements 371.9.1 Radiation Pattern Measurement 371.9.2 Gain Measurement 381.9.3 Polarization Measurement 381.9.4 Anechoic Chambers and Ranges 382 REVIEW OF ELECTROMAGNETIC WAVES 49Kao-Cheng Huang2.1 Maxwell’s Equations 492.1.1 Boundary Conditions 532.1.2 Equivalence Theorem 552.2 Antenna Parameters 562.2.1 Beam Solid Angle and Antenna Temperature 562.2.2 Directivity and Gain 582.2.3 Antenna Beamwidth 602.2.4 Aperture of a Lens 622.2.5 Phase Center 632.3 Polarization 642.4 Wave Propagation in Metamaterials 713 POLYROD ANTENNAS 77Kao-Cheng Huang3.1 Polyrods as Resonators 783.2 The Polyrod as a Radiator 833.2.1 Tapered Polyrod Antenna 853.3 Patch-Fed Circular Polyrod 903.4 Array of Polyrods 973.5 Multibeam Polyrod Array 1054 MILLIMETER WAVE LENS ANTENNAS 113Kao-Cheng Huang4.1 Millimeter Wave Characteristics 1144.1.1 Millimeter Wave Loss Factors 1144.1.2 Ray-Tracing Propagation 1174.2 Millimeter Wave Substrate Lens for Imaging 1214.3 Millimeter Wave and Submillimeter Wave Lens 1264.3.1 Extended Hemispherical Lens 1284.3.2 Off-Axis Extended Hemispherical Lens 1334.3.3 Submillimeter Wave Lens Antennas for Communications 1364.4 Analysis of Millimeter Wave Spherical Lens 1394.5 Waveguide-Fed Millimeter Wave Integrated Lens 1415 LENS ANTENNAS FOR COMMUNICATIONS FROM HIGH-ALTITUDE PLATFORMS 147John Thornton5.1 Introduction 1475.2 The High-Altitude Platform Concept 1485.2.1 Spectrum Reuse Using HAPs 1505.2.2 Example Results: Cell Power and Interference 1555.3 Advantages of Lenses over Reflector Antennas 1595.3.1 Reflectors 1605.3.2 Lenses 1615.3.3 Commercial Lens Antennas 1625.4 Development of a Shaped Beam Low-Sidelobe Lens Antenna with Asymmetric Pattern 1645.4.1 Primary Feed 1655.4.2 Symmetric 5° Beamwidth Antenna 1665.4.3 Asymmetric Beam 1665.4.4 Measurements 1745.5 Lens Antenna Payload Model 1775.6 Multifeed Lens 1785.7 Multiple Beam Spherical Lens Antennas for HAP Payload 1816 SPHERICAL LENS ANTENNAS 187John Thornton6.1 Introduction 1876.2 Spherical Lens Overview 1926.3 Analytical Methods 1956.3.1 Ray Tracing 1956.3.2 SWE 1976.3.3 Computational Method and Results 2026.3.4 Generic Feed Pattern 2066.3.5 Commercial Solvers 2086.4 Spherical Lens Materials and Fabrication Methods 2106.4.1 Machined Polymers 2106.4.2 Molding 2126.4.3 Polymer Foams 2126.4.4 PU Dielectric Loss 2146.4.5 Artifi cial Dielectrics 2156.5 Revisiting the Constant-Index Lens 2156.5.1 A Practical, Patch-Fed Hemispherical Constant-Index Lens 2196.5.2 Off-Axis Array-Fed Spherical Lens 2196.6 Cross-Polarization Properties of Spherical Lenses 2217 HEMISPHERICAL LENS-REFLECTOR SCANNING ANTENNAS 225John Thornton7.1 Introduction 2257.2 Candidate Scanning Antenna Technologies 2267.3 Spherical and Hemispherical Lens Antenna 2287.4 Hemispherical Lens Prototype 2297.5 Evolution of a Two-Layer Stepped-Index Polymer Lens 2327.6 A Hemispherical Lens-Reflector Antenna for Satellite Communications 2387.6.1 Requirements 2397.6.2 Lens Analysis 2407.6.3 Three-Layer Lens Geometry 2407.6.4 Lens Fabrication and Performance 2437.6.5 Mechanical Tracking System 2457.6.6 Ground Plane Effects 2497.6.7 Aperture Blockage in Scanning Lens Reflector 2517.7 A Low-Index Lens Reflector for Aircraft Communications (Contribution by D. Gray) 252About the Authors 267Index 268