本书系统地论述了现代雷达的构成、功能、信号和数据处理及应用，内容包括雷达的基本原理、功能、系统组成和性能指标，雷达天线，雷达发射机，雷达接收机，雷达显示和回波，雷达测量，雷达检测距离，雷达目标检测和跟踪，相干雷达信号处理，电子战术语与概念，雷达新技术和新体制等。全书内容全面，论述简明，由浅入深，注重基本原理与实际应用的联系。本书可作为信息与通信工程专业或雷达专业高年级本科生的课外辅导用书，也可作为雷达外训任务的教材，还可作为科技工作者和工程技术人员的参考书籍。

Preface This book comprehensively and systematically discusses the composition, function, signal and data processing and application of modern radar. Its content is based on the systematic collection of current domestic and foreign research materials and the author’s teaching materials. It is mainly composed of five major parts, a total of 11 chapters. The first part is an overview and basic principles of radar (Chapter 1). It mainly introduces the basic principles, functions, system composition and performance indicators of radar, including the basic concepts of radar, classification of radar, electromagnetic wave propagation, radar function, radar frequency division and selection, impact on radar performance, target type, basic principles of target detection under noise background, signal-to-noise ratio under noise background. This part lays the foundation for the subsequent introduction of radar subsystem and signal processing. The second part mainly introduces the radar subsystem (Chapter 2-5). They are radar antenna, transmitter, receiver and display, respectively introducing their characteristics and functions, main types, performance parameters and their impact on radar detection performance. The focus is on the performance parameters of each subsystem, such as beam pattern, antenna polarization, gain, pulse waveform parameters, receiver sensitivity, dynamic range, etc. Finally, the new system applications of each subsystem will be introduced, such as solid-state transmitters, phased array principles, dual-band radars, and software radars. The third part mainly introduces the processing flow and performance parameters of modern radar (Chapter 6-8), focusing on the principle of parameter measurement and detection of radar, including four chapters. Chapter 6 mainly introduces the parameter measurement of radar, including distance measurement (pulse ranging, distance blind zone, maximum operating distance, range resolution, maximum unambiguous distance, etc.), angle measurement (amplitude method angle measurement, monopulse angle measurement, angle resolution, etc.), velocity measurement (Doppler Effect, Doppler frequency shift, velocity resolution, maximum unambiguous velocity, etc.). Chapter 7 mainly derives radar equations and radar line-of-sight distance, from the perspective of radar detection distance, combined with the process of radar target detection, and the factors that affect radar detection distance are discussed. Chapter 8 mainly introduces the radar target detection technology, the detection process, the judgment of the threshold, the influence of the signal-to-noise ratio on the detection, the Constant False Alarm Rate (CFAR) detection, etc. The data processing mainly includes the introduction of radar data processing, the basic concepts of radar tracking and the basic method of target tracking. The fourth part introduces the most commonly used processing mode of modern radar signal processing, namely coherent signal processing (Chapter 9). It mainly introduces coherent radar signal processing, Moving Target Indication (MTI), Moving Target Detection (MTD), signal integration, etc. The fifth part is about radar electronic warfare and the modern radar system (Chapters 10 and 11). Radar electronic warfare focuses on radar applications in complex electromagnetic environments, covering the three parts of radar electronic warfare, including the basic terms, concepts and applications of electronic warfare support, electronic attack and protection. The last chapter focuses on new radar technologies and modern systems, such as low probability intercept radar, multifunction rotating electronically scanned radar, ultra-wideband radar, noise radar, MIMO radar, high-resolution SAR imaging radar, ground penetrating radar, etc. It helps the reader have a certain understanding of the future development trend and technology of radar. The book is accompanied by mind maps. The whole book and each chapter are summarized by means of mind maps, covering all important knowledge points. It is logical and systematic, which is convenient for readers to sort out the knowledge points and easy to remember. The content of this book is comprehensive; the discussion is concise, from the shallower to the deeper, focusing on the connection between basic principles and practical applications. It can be used as an extracurricular tutoring book for senior undergraduates majoring in information and communication engineering or radar, and can also be used as a textbook for related colleges and universities engaged in radar training tasks, and it can also be used for scientific and technological workers engaged in research on radar signal processing and target detection, providing reference for engineering and technical personnel. In the process of writing this book, Professor Kang Jian, Professor Guan Jian, Professor Sun Baoliang, Professor Zhang Hai of Naval Aviation University gave careful guidance and help. The completion of this book has also received strong support from many colleagues and students. They are Xue Yonghua, Zhang Caisheng, Zhang Lin, Deng Bing. I would like to express my sincere thanks to them. Due to time limitations and limited authorship, omissions and errors in the book are unavoidable. Readers are welcomed to criticize and correct. Chen Xiaolong Yantai, December 2020

Contents Chapter 1 An Introduction to Radar 1 1.1 Fundamental Elements of Radar 2 1.1.1 The Radar Concept 2 1.1.2 Types of Radar 5 1.1.3 Radar Medium 9 1.2 A Brief History of the Evolution of Radar 9 1.2.1 Early Experiments 9 1.2.2 First Military Radars 10 1.3 Functions Performed by Radar 12 1.3.1 Overall System Considerations 12 1.3.2 Basic Radar Functions 14 1.4 Radar Frequency 16 1.4.1 Radar Frequency Division 16 1.4.2 Influence of Frequency on Radar Performance 19 1.5 Some Definitions and Other Details 22 1.5.1 Types of Radar Targets 22 1.5.2 Target Fluctuation Models 23 1.5.3 Noise, Signal-to-Noise Ratio, and Detection 24 Chapter 2 Radar Antenna 27 2.1 Distribution of Radiated Energy in Angle 29 2.2 Types of Radar Antennas 34 2.2.1 Yagi Antennas 34 2.2.2 Reflector Antennas 36 2.2.3 Phased Array Antennas 40 2.3 Characteristics of the Radiation Pattern 45 2.4 Phase Scanning 51 Summary 55 Chapter 3 Radar Transmitter 57 3.1 Requirements for Transmitters 57 3.2 Summary of Radar RF Power Sources 58 3.2.1 Oscillator 61 3.2.2 Tube Amplifiers 63 3.2.3 Solid-State RF Power Sources 66 3.3 Two Basic Transmitter Configurations 68 3.3.1 Self-excited Oscillator 68 3.3.2 Power Oscillator 68 3.3.3 The Pulse Modulator 70 3.4 Pulsed Waveform 72 3.5 Coherent Radar 83 3.5.1 Concept of Coherence 83 3.5.2 Fully Coherent Radar 84 3.5.3 Solid-State Amplifier 87 Summary 88 Chapter 4 Radar Receiver 90 4.1 Summary of Receiver Types 91 4.1.1 Crystal Video Receiver 92 4.1.2 Homodyne Receivers 93 4.1.3 Superheterodyne Receivers 94 4.2 Major Receiver Functions 99 4.2.1 Receiver Protection 99 4.2.2 RF Preselection 100 4.2.3 Frequency Downconversion and Mixers 101 4.2.4 Selection of LO and IF Frequencies 102 4.3 Electrical Background Noise 103 4.4 Receiver Dynamic Range 108 4.4.1 Sensitivity Time Control (STC) 110 4.4.2 Gain Control 111 Summary 112 Chapter 5 Radar Display and Returns 113 5.1 Radar Displays 114 5.2 Radar Clutter 118 5.2.1 Introduction to Radar Clutter 118 5.2.2 General Dependencies of Surface Clutter 121 5.2.3 Sea Clutter 122 Chapter 6 Radar Measurements 127 6.1 Range Measurements 128 6.1.1 Pulse Ranging Method 128 6.1.2 Minimum Range 128 6.1.3 Maximum Range 129 6.1.4 Range Resolution 130 6.1.5 Pulse Compression 132 6.2 Direction Measurements 136 6.2.1 Lobing Angle Measurement 137 6.2.2 Monopulse Angle Measurement 138 6.3 Velocity Measurements 143 6.3.1 Doppler Effect 143 6.3.2 Doppler Shift 144 6.3.3 Unambiguous Doppler Shift Measurement 147 Summary 148 Chapter 7 The Radar Detection Range 150 7.1 What Determines Detection Range 151 7.2 Radar Range Equation 154 7.2.1 Power Density at a Distance R 154 7.2.2 Received Power from a Target 155 7.2.3 Signal-to-Noise Ratio and the Radar Range Equation 157 7.2.4 Summary of Losses 158 7.2.5 Solving For Other Variables 159 7.2.6 Decibel Form of the Radar Range Equation 159 7.2.7 Radar Line of Sight (RLOS) 161 7.2.8 Radar Reflections from Flat Ground 162 7.2.9 The Radar Equation in Practice 163 7.3 What the Range Equation Tells Us 165 7.4 Surface Clutter Radar Equation 169 Summary 171 Chapter 8 Fundamental of Radar Detection and Tracking 173 8.1 Detection Process 173 8.2 Integration and Its Leverage on Detection Range 177 8.2.1 Integration Experiment 177 8.2.2 Multiple-Pulse Effects on Radar Equation 181 8.3 Parameters of Radar Detection 183 8.3.1 Detection Probability 183 8.3.2 False-Alarm Rate 184 8.3.3 Detection Threshold 185 8.3.4 Signal-to-Noise Ratio 187 8.4 Constant False Alarm Rate Detector 189 8.4.1 Basic CFAR Architecture 190 8.4.2 Cell Averaging CFAR 192 8.5 Tracking with Radar 195 8.5.1 Types of Tracking 195 8.5.2 Radar Range Tracking 197 8.6 Radar Signal Management 201 Summary 203 Chapter 9 Coherent Radar Signal Processing 204 9.1 Pulsed Radar Doppler Data Acquisition and Characteristics 206 9.2 Moving Target Indication (MTI) 208 9.2.1 Basic Principle 208 9.2.2 Pulse Cancellers 210 9.2.3 Blind Speeds 212 9.2.4 Merits and Limitations 213 9.3 Pulse-Doppler Processing 215 9.3.1 Basic Principle 215 9.3.2 Doppler Filter Bank 217 9.3.3 Metrics for Pulse-Doppler Detection of Moving Targets 219 9.3.4 The Moving Target Detector (MTD) 221 Summary 225 Chapter 10 Electronic Warfare Terms and Concepts 226 10.1 EW Definition 226 10.2 EW Subfields 226 10.3 Electronic Warfare Support 227 10.4 Electronic Attack 233 10.5 Electronic Protection 240 Summary 242 Chapter 11 New Technology and System of Radar 243 11.1 Low Probability of Intercept (LPI) Radar 243 11.2 Multifunction Rotating Electronically Scanned Radars 245 11.3 Ultra Wide-Band (UWB) Radar 246 11.4 Noise Radar Technology 247 11.5 Multi-Input Multi-Output (MIMO) Radar 248 11.6 Synthetic Aperture Radar (SAR) 249 11.7 Air-Defense Radars 251 11.8 Ground Penetrating Radar (GPR) 252 Reference 256