Concepts and Applications

Microwave Engineering

Sanjay Kumar
Air Commodore

IAF, 9 BRD, Pune

Formerly, Principal Advisor

Defence Avionics Research Establishment (DARE)

DRDO, Bangalore

Saurabh Shukla

Scientist
Defence Avionics Research Establishment (DARE)
DRDO, Bangalore

PHI Learning PfcO© fc8(fe(i

Delhi-110092

.2014
 CONTENTS

Preface xvii
Standard Prefixes, Physical Constants, and Conductivity xix

1. INTRODUCTION TO MICROWAVES
1.1 Introduction 7
1.2 Brief HistoricalDevelopment 7
1.3 Electromagnetic (EM) Spectrum 2
1.4 International Telecommunication Union (ITU) 4
1.5 Institute of Electrical and Electronics Engineers (IEEE) 5
1.6 Salient Features of Microwaves 5
1.7 Advantages and Disadvantages of Microwaves 7
1.8 Microwaves Applications 7
1.9 Commercial Applications of Radio and Microwave Spectrum
1.10 Microwave Propagation 77
1.11 Atmospheric Effects 11
1.12 Temperature Inversion and Ducting 7J
1.13 Effects of Attenuation 13
1.14 Ground (Surface) Waves 74

1.15 Calculation of Electric Field Strength at a Distance 15

1.16 Effects of Ground Waves on Radars 16
1.17 Plasma Effect 76
1.18 The Ionosphere and Its Effects 77

Summary 18
Review Questions 19

Multiple Choice Questions 20

2. TRANSMISSION LINES AND WAVEGUIDES

2.1 Introduction 23

2.2 Some Important Vector Operations 23

vii
Viii Contents

25
2.3 Time and Frequency Domain Representation
2.4 Maxwell's Equations 25
2.5 Transmission Lines in Microwaves 27

2.6 Helmholtz Equation or Vector Wave Equation 28

2.6.1 Attenuation and Phase Constant 29

2.7 Relationship between Decibels and Nepers 29

2.8 Types of Medium 31

2.9 Skin Depth 31

2.10 Skin Effect 32

2.11 General Solution of Vector Wave Equation 32

2.12 Rectangular Waveguide 35

2.13 Modes 35
TE Mode of Rectangular Waveguide 35
2.14 Analysis
2.14.1 Boundary Conditions 38
2.14.2 Cut-off Wave Number 38

2.14.3 Cut-off Frequency 39

2.14.4 Dominant Mode 39

2.14.5 Phase Constant 39
2.14.6 Phase Velocity 39

2.14.7 Guide Wavelength 39

2.14.8 Characteristic Impedance 40
2.14.9 Dominant Mode in Rectangular Waveguide 40

2.14.10 Degenerative Modes 40

2.15 TM Mode Analysis of Rectangular Waveguide 41

2.15.1 Boundary Condition 42
2.15.2 Cut-off Wave Number 43

2.15.3 Cut-off Frequency 43

2.15.4 Phase Constant 43

2.15.5 Phase Velocity 43

2.15.6 Guide Wavelength 43

2.15.7 CharacteristicImpedance 43

2.16 Power Transmission in Rectangular Waveguide 44

2.17 Microwave Cavities 46

2.17.1 Application 46

2.18 Rectangular Cavity Resonator 46

2.18.1 Resonant Frequency 47

2.19 Circular Waveguide 48

2.20 TE Mode Analysis of a Circular Waveguide 51

2.20.1 Boundary Conditions 53

2.20.2 Cut-off Frequency 54
2.20.3 Phase Constant 54

2.20.4 Phase Velocity 54

2.20.5 Guide Wavelength 54

2.20.6 Characteristic Impedance 54

2.21 TM Mode Analysis in Circular Waveguide 55

2.21.1 Boundary Condition 55

2.21.2 Cut-off Frequency 56

 2.21.3 Phase Constant 56
2.21.4 Phase Velocity 56

2.21.5 Guide Wavelength 56

2.21.6 Characteristic Impedance 57

2.22 Circular Cavity Resonator 58

2.23 TEM Mode 59
2.24 Power Transmission in a Circular Waveguide 61

2.25 Characteristic Impedance of a Coaxial Line 62

2.26 Power Transmission in a Coaxial Line 63

2.27 Power Loss in Waveguides 63

2.28 Mode Excitation in Waveguides 64

2.28.1 Rectangular Waveguide Modes and Excitation 64
2.28.2 Circular Waveguide Modes and Excitation 65

2.29 Quality Factor 66

2.29.1 Unloaded Quality Factor 66
2.29.2 Externa] Quality Factor 66
2.29.3 Loaded Quality Factor 67

2.30 Unloaded Quality Factor of Rectangular Cavity Resonator

2.31 Unloaded Quality Factor of Circular Cavity Resonator 68

Summary 69
Review Questions 70

Multiple Choice Questions 71

Numerical Problems 73

PLANAR TRANSMISSION LINES

3.1 Introduction 74
3.2 Microstrip Line 74
3.2.1 Microstrip Line Variants 78

3.3 Stripline 80
3.3.1 Different Versions of Stripline 83

3.4 Slotline 55
3.4.1 Slotline Variants 87

3.5 Coplanar Waveguides 87

3.6 Finline 88
3.7 Comparison between Planar Transmission Lines 89

3.8 Coupled Lines 90

3.8.1 Even Mode 90

3.8.2 Odd Mode 91
3.8.3 Planar Transmission Lines 91
Coupled
3.9 Transitions 92
3.9.1 Coaxial Line to Microstrip Transition 93

3.9.2 Coaxial Line to Waveguide Transition 94

3.9.3 Microstrip Transition 95

Waveguide to

3.9.4 Microstrip to Slotline Transition 96

X Contents

3.10 Discontinuities 96
3.10.1 Short Circuit 97

3.10.2 Open Circuit 97

3.10.3 Air Bridges 97
3.10.4 Bends and Corners 97

3.10.5 Steps 98
3.10.6 T-junctions 99

3.11 Dielectric Substrates 99

Summary 100
Review Questions 101

Multiple Choice Questions 101

Numerical Problems 103

4. NETWORK ANALYSIS AND MICROWAVE PASSIVE COMPONENTS

4.1 Introduction 104
4.2 Two Port Network 104
4.2.1 Transfer Matrix 705
4.2.2 Impedance Matrix 105
4.2.3 Admittance Matrix 105
4.2.4 Scattering Matrix 105
4.2.5 Properties of 5-Matrix 106
4.2.6 Parameter Conversion 108
4.3 E-Plane Tee Junction/Series TEE 109
4.3.1 Input Output Power 111
4.4 H-plane Tee Junction/Shunt Tee 113
AAA Input Output Power 114
4.5 Magic Tee (E and H-plane Tee) 116
4.5.1 Input Output Power 118
4.5.2 Applications of MagicTee 119
4.6 Hybrid Ring 122
4.7 Directional Coupler 124
4.8 Smith Chart 127
4.9 Quarter Wave Transformer 132
4.10 Circulator 135
4.11 Isolator 136

Summary 137

Review Questions 137

Multiple Choice Questions 138
Numerical Problems 140

5. MICROWAVE TUBE BASED AMPLIFIERS

5.1 Introduction 141

5.2 Limitation of Conventional Vacuum Tubes 141
5.3 Microwave Tubes 142
 Contents XI

5.4 Klystron 143

5.4.1 Analogy between Klystron and Pipe Organ Tube 143
5.4.2 General Principle of Operation of Klystron 143
5.4.3 Two Cavity Klystron 143
5.4.4 Working Principle of Two Cavity klystron 144
5.4.5 Bunching and RF Amplification 144
5.4.6 Multi Cavity Power Klystron 145
5.4.7 Reflex Klystron 145
5.4.8 Reflex Klystron Construction Details 145
5.4.9 Reflex Klystron Working Principle 146
5.4.10 Reflex Klystron Bunching and RF Amplification 146
5.4.11 Applegate Diagram 147
5.4.12 Performance Characteristics 147
5.4.13 Application of Reflex Klystron 147
5.5 Magnetron 149
5.5.1 Construction Details 149
5.5.2 Working Principle 750
5.5.3 Bunching and RF Amplification 757
5.5.4 Strapping 752
5.5.5 Modes of Operation 752
5.5.6 Tunable Magnetrons 752
5.5.7 Performance Characteristics 752
5.5.8 Applications of Magnetron 7JJ
5.6 Travelling Wave Tube (TWT) 153
5.6.1 Construction Details 753

5.6.2 Working Principle 154

5.6.3 Bunching and RF Amplification 154
5.6.4 Performance Characteristics 755
5.6.5 Coupled Cavity TWT 755
5.6.6 Construction 756
5.6.7 Working Principle 756
5.6.8 Applications of TWT 756

5.7 Crossed Field Amplifier (CFA) 757

5.7.1 Construction Details 757
5.7.2 Working Principle 755
5.7.3 Bunching and RF Amplification 755
5.7.4 Performance Characteristics 755
5.7.5 Application of CFA 755
5.8 Backward Wave Oscillator (BWO) 159
5.8.1 Construction Details of O-type 759
5.8.2 Working Principle 760
5.8.3 Performance Characteristics 760
5.8.4 Applications of BWO 760

Summary 160
Review Questions 161

Multiple Choice Questions 162

Numerical Problems 164
Xii Contents

6. MICROWAVE SOLID STATE AMPLIFIERS 166-209

6.1 Introduction 166

6.2 Microwave Junction Transistor (BJT) 766"

Bipolar
6.2.1 BJT Configurations 767
6.2.2 Limitations 767

6.3 Heterojunction Bipolar Transistor (HBT) 168

6.3.1 Device Structure 168
6.3.2 Principle 765
6.3.3 Operating Principle 769

6.4 Tunnel Diode 770

6.4.1 Operation 777

6.5 Field Effect Transistor (FET) 775

6.6 Junction Field Effect Transistor (JFET) 176
6.6.1 Operating Principle 776

6.7 Metal Semiconductor Field Effect Transistor (MESFET) 775

6.7.1 Construction 178
6.7.2 Principle of Operation 178

6.8 High Electron Mobility Transistor (HEMT) 779

6.8.1 Construction 779
6.8.2 Operational Mechanism 779
6.8.3 Current-Voltage Characteristics (I-V Characteristics) 779

6.9 Metal Oxide Semiconductor Field Effect Transistor (MOSFET) 180

6.9.1 Construction 180
6.9.2 Operational Mechanism 180
6.10 Charge Coupled Devices (CCD) 182
6.10.1 Operational Mechanism 782

6.11 Gunn Diode 183

6.11.1 Construction Details 183
6.11.2 Working Principle 184
6.11.3 Negative Resistance Property of Gunn Diode 185

6.11.4 Gunn Diode as Oscillator 786

6.11.5 Advantages of Gunn Oscillator 787
6.11.6 Disadvantages of Gunn Diode 787
6.11.7 Gunn Diode Applications 787
6.12 Read Diode 758
6.12.1 Structure 788
6.12.2 Operating Principle of Read Diode Oscillator 789
6.12.3 Concept of Avalanche Breakdown 797
6.13 Avalanche Diode 792
6.14 IMPATT Diode 792
6.14.1 Construction 792

6.14.2 Operating Principle 795

6.14.3 Advantages of IMPATT Diode 795
6.14.4 Disadvantages of IMPATT Diode 795
6.14.5 Applications of IMPATT Diode 795
 • • •

Contents Xlll

6.15 TRAPATT Diode 196

166-209
6.15.1 Structure 796
6.15.2 Operating Principle 796
6.15.3 Advantages of TRAPATT Diode 797
6.15.4 Disadvantages of TRAPATT Diode 797
6.15.5 Applications of TRAPATT Diode 797
6.16 BARITT Diode 797
6.16.1 Structure 795
6.16.2 Operating Principle 795
6.16.3 Advantages of BARITT Diode 200

6.16.4 Disadvantages of BARITT Diode 200

6.16.5 Applications of BARITT Diode 200
6.17 Parametric Amplifiers 201
6.17.1 Amplification Process 207

6.18 Analogy between Parametric Amplifier and Superhetrodyne Mixer 201

6.18.1 Working Principle of Parametric Degenerate Amplifier 202
6.18.2 Advantages of Parametric Amplifier 203
6.18.3 Disadvantages of Parametric Amplifier 203
6.18.4 Applications of Parametric Amplifiers 203

Summary 204
Review Questions 206

Multiple Choice Questions 207

Numerical Problems 209

7. MICROWAVE MEASUREMENTS 210-234

7.1 Introduction 210

7.2 Microwave Detection 210

7.2.1 Tunable Detectors 277
7.2.2 Detector Mounts 277
7.3 Slotted Line 212

7.4 Power Measurement 213

7.4.1 Calorimetric Method 213
7.4.2 Bolometer Method 275
7.4.3 Thermocouple Method 275

7.4.4 Diode Detector Method 276

7.5 Frequency Measurement 276

7.5.1 Slotted Line Method 276
7.5.2 Resonant Cavity Method 278
7.5.3 Counter Method 218

7.6 Impedance Measurement 279

7.6.1 Impedance Measurement by Slotted Line 279

7.6.2 Impedance Measurement by Reflectometer Method 227

7.7 VSWR Measurement 227

7.7.1 VSWR Measurement by Slotted Line 227

7.7.2 Double Minimum Method 222

Xiv Contents

7.8 Attenuation Measurement 222

7.8.1 Power Ratio Method 223

7.8.2 RF Substitution Method 223

7.9 Insertion Loss Measurement 224

7.10 Microwave Instruments 225
7.10.1 VSWR Meter 225
7.10.2 Spectrum Analyser 225
7.10.3 Network Analyser 227
7.10.4 Power Meter 228

Summary 230
Review Questions 231

Multiple Choice Questions 232

Numerical Problems 234

8. ANTENNA SYSTEMS 235-27

8.1 Introduction 235

8.2 Isotropic Antenna 236
8.3 Types of Antenna 236
.8.4 Omnidirectional Antenna 237
8.5 Directional Antenna 238
8.6 Radiation Mechanism of an Antenna 238
8.7 Resonant Antenna 240

8.8 Nonresonant Antennas 241.

8.9 Microwave Antenna 242

8.10 Parabolic Reflector or Parabolic Dish 242

8.10.1 Salient Features of Parabolic Reflector 243
8.10.2 Feed Mechanisms 244
8.10.3 Design Issues of Parabolic Antenna 245
8.10.4 Problem Associated with Parabolic Reflector 247
8.11 Horn Antenna 247
8.12 Yagi-Uda Antenna 248
8.13 Helical Antenna 249
8.14 Log Periodic Antenna 250
8.15 Loop Antenna 251

8.16 Lens Antenna 252

8.17 Phased Arrays 253

8.18 Gain and Directivity 255
8.19 Radiation Efficiency 256
8.20 Aperture Area Efficiency
or 256
8.21 Effective Aperture 256
8.22 Bandwidth 256
8.23 Radiation Pattern 257
8.24 Beamwidth, Lobes and Nulls 257
 Contents XV

8.25 Antenna Resistance 258

8.25.1 Radiation Resistance 258
8.25.2 Antenna Losses 258

8.26 Polarisation 258

8.27 Modern Antennas 261
.
8.27.1 Vivaldi Antenna 261

8.27.2 Patch Antenna 263

8.27.3 Sinuous Antenna 264
8.27.4 Conformal Antenna 265

8.27.5 Shared Aperture Antenna 266

8.28 Challenges for Antenna Designers 267

8.28.1 Resource Crunch 267
8.28.2 Time and Money 267

8.28.3 Stringent Parameters 268

Summary 268

Review Questions 269

Multiple Choice Questions 270

Numerical Problems 271

9. RADAR SYSTEMS 272-303

9.1 Introduction 272

9.2 Purpose of Radar 272

9.3 Types of Radar Based on Techniques 272

9.4 Classification of Radar Based on Functionalities and Applications 273

9.5 Basic Radar System 274

9.6 and Powers Used in Radar 275
Frequency
9.7 The Radar Range Equation 276

9.8 Important Deductions of Range Equation 277

9.9 Peak Power and Average Power in Radar 278
279
9.10 Pulse Repetitive Frequency (PRF) and Range Ambiguities
9.11 Range Resolution 280

9.12 Radar Cross-section 281

9.13 Types of Display in Radar 282
9.13.1 Plan Position Indicator (PPI) 283

9.13.2 A-Scope 283

9.13.3 B-Scope 284

9.13.4 C-Scope 284
9.13.5 D-Scope 284

9.13.6 E-Scope 284

9.13.7 Range Height Indicator (RHI) 284

9.14 Basic Doppler Radar or CW Radar 284

9.14.1 Police Radar Based on Doppler Principle 286

9.15 of Range Measurement 287

Principle
9.16 FM CW Radar 288
9.17 of Pulse Radar 289
Operation
XVi Contents

9.18 Indicator(MTI) Radar 290

Moving Target
9.18.1 Clutter Suppression Technique in MTI Radar 292

9.19 Blind Speed in MTI Radar 292

9.20 Search Acquisition and Tracking Radar 293

9.21 Methods of Acquiring Track Data by Tracking Radars 294

9.21.1 Sequential Lobing 294

9.21.2 Conical Scan 296

9.21.3 Monopulse Tracking Technique 297

Summary 299
Review Questions 299

Multiple Choice Questions 300

Numerical Problems 302

10. SATELLITE COMMUNICATION 304-328

10.1 The Genesis of Satellite Communication 304

10.2 Brief History of Satellite Communications 304
10.3 Basics of Satellite Communication 305
10.4 Satellite Orbits 307

10.5 Types of Satellite Communication Systems 309

10.6 Earth Station 310
10.7 Need for Satellite Communication 311
10.8 Advantages of Satellite Communication 311
10.9 Limitations of Satellite Communication 312

10.10 Frequency Bands Used for Satellite Communication 313

10.11 Applications of Satellites 313

10.12 Link Design and Friis Transmission Equation 315

10.13 Link
Design 318
10.14 System Noise Temperature 320
10.15 Calculation of System Noise Temperature 322
10.16 Noise Figure (NF) and Noise Temperature 323
10.17 G/T Ratio for Earth Stations 324

Summary 325

Review Questions 326

Multiple Choice Questions 326

Numerical Problems 328

REFERENCES 329-332

INDEX 333-336