Conformal Array Antenna Theory and Design

Preface xi

Abbreviations and Acronyms xiii

1 Introduction 1

1.1 The Definition of a Conformal Antenna 1

1.2 Why Conformal Antennas? 2

1.3 History 4

1.4 Metal Radomes 9

1.5 Sonar Arrays 9

2 Circular Array Theory 15

2.1 Introduction 15

2.2 Fundamentals 16

2.3 Phase Mode Theory 23

2.4 The Ripple Problem in Omnidirectional Patterns 34

2.5 Elevation Pattern 41

2.6 Focused Beam Pattern 41

3 The Shapes of Conformal Antennas 49

3.1 Introduction 49

3.2 360° Coverage 52

3.3 Hemispherical Coverage 57

3.4 Multifaceted Surfaces 67

3.5 References 70

4 Methods of Analysis 73

4.1 Introduction 73

4.2 The Problem 75

4.3 Electrically Small Surfaces 76

4.4 Electrically Large Surfaces 89

4.5 Two Examples 95

4.6 A Comparison of Analysis Methods 100

5 Geodesics on Curved Surfaces 123

5.1 Introduction 123

5.2 Singly Curved Surfaces 130

5.3 Doubly Curved Surfaces 135

5.4 Arbitrarily Shaped Surfaces 149

6 Antennas on Singly Curved Surfaces 155

6.1 Introduction 155

6.2 Aperture Antennas on Circular Cylinders 157

6.3 Aperture Antennas on General Convex Cylinders 192

6.4 Aperture Antennas on Faceted Cylinders 200

6.5 Aperture Antennas on Dielectric Coated Circular Cylinders 209

6.6 Microstrip-Patch Antennas on Coated Circular Cylinders 230

6.7 The Cone 245

7 Antennas on Doubly Curved Surfaces 265

7.1 Introduction 265

7.2 Aperture Antennas 267

7.3 Microstrip-Patch Antennas 289

8 Conformal Array Characteristics 305

8.1 Introduction 305

8.2 Mechanical Considerations 306

8.3 Radiation Patterns 313

8.4 Array Impedance 327

8.5 Polarization 336

8.6 Characteristics of Selected Conformal Arrays 351

9 Beam Forming 365

9.1 Introduction 365

9.2 A Note on Orthogonal Beams 366

9.3 Analog Feed Systems 366

9.4 Digital Beam Forming 380

9.5 Adaptive Beam Forming 384

9.6 Remarks on Feed Systems 388

10 Conformal Array Pattern Synthesis 395

10.1 Introduction 395

10.2 Shape Optimization 397

10.3 Fourier Methods for Circular Ring Arrays 397

10.4 Dolph-Chebysjev Pattern Synthesis 398

10.5 An Aperture Projection Method 401

10.6 The Method of Alternating Projections 404

10.7 Adaptive Array Methods 406

10.8 Least-Mean-Squares Methods (LMS) 407

10.9 Polarimetric Pattern Synthesis 409

10.10 Other Optimization Methods 409

10.11 A Synthesis Example Including Mutual Coupling 411

10.12 A Comparison of Synthesis Methods 414

11 Scattering From Conformal Arrays 421

11.1 Introduction 431

11.2 Definitions 422

11.3 Radar Cross Section Analysis 423

11.4 Cylindrical Array 427

11.5 Cylindrical Array with Dielectric Coating 435

11.6 Radiation and Scattering Trade-off 446

11.7 Discussion 458

References 459

Subject Index 463

About the Authors 471