EM Detection of Concealed Targets

THE LATEST EM TECHNIQUES
FOR DETECTING CONCEALED TARGETS, WHETHER EXPLOSIVES, WEAPONS, OR PEOPLE

Extensively illustrated from basic principles to system design, the fundamental concepts of RF, microwave, millimeter wave, and terahertz detection systems and techniques to find concealed targets are explained in this publication. These concealed targets may be explosive devices or weapons, which can be buried in the ground, concealed in building structures, hidden under clothing, or inside luggage. Concealed targets may also be people who are stowaways or victims of an avalanche or earthquake.

Although much information is available in conference proceedings and professional society publications, this book brings all the relevant information in a single, expertly written and organized volume.

Readers gain an understanding of the physics underlying electromagnetic (EM) detection methods, as well as the factors that affect the performance of EM detection equipment, helping them choose the right type of equipment and techniques to meet the demands of particular tasks. Among the topics covered are:

• Ultra-wideband radar and ground-penetrating radar

• Millimeter, sub-millimeter, and terahertz systems

• Radar systems including Doppler, harmonic, impulse, FMCW, and holographic

• Radiometric systems

• Nuclear quadrupole resonance systems

Author David Daniels has many years of experience designing and deploying EM systems to detect concealed targets. As a result, this publication is essential for scientists and engineers who are developing or using EM equipment and techniques for a diverse range of purposes, including homeland security, crime prevention, or the detection of persons.

Autorentext

DAVID J. DANIELS, BSC, MSC, CENG, FIET, SMIEE, is the Chief Consultant for Sensors at Cobham Technical Services (formerly known as ERA Technology). David has more than thirty years of experience in the development of radar, acoustic, and electromagnetic systems as well as products for security, sensing, and test applications for the military and commercial enterprises. He has brought such products to market as acoustic detection systems, fiber optic cryogenic liquid leak sensors, marine radar rescue transponders, ultra-wideband microwave amplifiers, ground-penetrating radar, land-mine detectors, and RF and microwave security systems. His current interests center on sensor systems for land-mine detection, homeland security, and military counterterrorist activities.

Zusammenfassung
THE LATEST EM TECHNIQUES FOR DETECTING CONCEALED TARGETS, WHETHER EXPLOSIVES, WEAPONS, OR PEOPLE Extensively illustrated from basic principles to system design, the fundamental concepts of RF, microwave, millimeter wave, and terahertz detection systems and techniques to find concealed targets are explained in this publication. These concealed targets may be explosive devices or weapons, which can be buried in the ground, concealed in building structures, hidden under clothing, or inside luggage. Concealed targets may also be people who are stowaways or victims of an avalanche or earthquake. Although much information is available in conference proceedings and professional society publications, this book brings all the relevant information in a single, expertly written and organized volume. Readers gain an understanding of the physics underlying electromagnetic (EM) detection methods, as well as the factors that affect the performance of EM detection equipment, helping them choose the right type of equipment and techniques to meet the demands of particular tasks. Among the topics covered are:

• Ultra-wideband radar and ground-penetrating radar
• Millimeter, sub-millimeter, and terahertz systems
• Radar systems including Doppler, harmonic, impulse, FMCW, and holographic
• Radiometric systems
• Nuclear quadrupole resonance systems Author David Daniels has many years of experience designing and deploying EM systems to detect concealed targets. As a result, this publication is essential for scientists and engineers who are developing or using EM equipment and techniques for a diverse range of purposes, including homeland security, crime prevention, or the detection of persons.

Inhalt
Preface xi

Acknowledgments xiii

List of Frequently used Acronyms xv

1 Introduction 1

1.1 Scope and Objectives 1

1.2 Structure 2

1.3 Market Needs for Security 2

1.4 Targets inside Containers 5

1.5 Buried Land Mines 5

1.6 Forensic Detection of Buried Bodies 6

1.7 Avalanche and Earthquake Victims 7

1.8 Concealed Humans 7

1.9 Concealed Targets on Humans 8

1.10 Radiological Considerations 8

1.11 Licensing Considerations 10

1.12 Statistics of the Detection Performance of a Sensor 12

1.13 Summary 19

2 Physics of Propagation 20

2.1 Introduction 20

2.2 Propagation of Electromagnetic Fields in Free Space 21

2.2.1 Reactive Fields 22

2.2.2 Near Fields 23

2.2.3 Far Fields 23

2.2.4 Polarization 24

2.2.5 Radar Cross Section 27

2.2.6 Reflection 30

2.2.7 Refraction 31

2.2.8 Brewster Angle 31

2.2.9 Dispersion 33

2.2.10 Anisotropy 33

2.2.11 Clutter 33

2.3 Propagation of Energy in a Dielectric 35

2.3.1 Introduction 35

2.3.2 Velocity in a Dielectric 37

2.3.3 Impedance of a Dielectric 38

2.3.4 Propagation Loss in a Dielectric 39

2.3.5 Coupling Losses into Materials 44

2.4 Dielectric Properties of Soils and Rocks 45

2.5 Propagation in Water 51

2.6 Atmospheric Absorption of Electromagnetic Waves 53

2.6.1 Rain and Fog 55

2.6.2 Dust, Smoke, and Sand Storms 57

2.7 Attenuation of Electromagnetic Fields by Materials 59

2.7.1 Human and Animal 59

2.7.2 Heartbeat 61

2.7.3 Respiration 62

2.7.4 Clothing 66

2.7.5 Construction Materials 71

2.7.6 Explosives 76

2.8 Summary 82

3 Antennas 83

3.1 Introduction 83

3.2 Antenna Parameters 85

3.2.1 Antenna Directivity 85

3.2.2 Antenna Gain 86

3.2.3 Antenna Efficiency 88

3.2.4 Side Lobes and Back Lobes 88

3.2.5 Bandwidth 88

3.2.6 PolarizationLinear, Elliptical, and Circular 89

3.2.7 Antenna Phase Center 89

3.2.8 Antenna Patterns 90

3.2.9 Time Side Lobes and Ring-down 91

3.2.10 Antenna Footprint 93

3.3 Aperture Antennas 95

3.4 Antennas for Proximal Operation 97

3.4.1 Introduction 97

3.4.2 Coupling Energy into the Ground or a Dielectric 98

3.5 Linear Phase Antennas 101

3.5.1 Dipoles 101

3.5.2 Loaded Antennas 103

3.5.3 BiConical Antennas 106

3.5.4 Bow-Tie Antennas 107

3.5.5 Dielectric Road Antennas 108

3.5.6 TEM Horn Antennas 109

3.5.7 Impulse Radiating Antennas 115

3.6 Nonlinear Phase Antennas 117

3.6.1 Vivaldi Antennas 118

3.6.2 Equiangular Antennas 119

3.6.3 Horn Antennas 120

3.7 Antenna Arrays 121

3.8 Summary 126

4 Nuclear Quadrupole Resonance 128

4.1 Introduction 128

4.2 Pulse Sequences 131

4.3 System Design 138

4.3.1 Introduction 138

4.3.2 Transmit-and-Receive Coils 139

4.3.3 Receiver and Coil Considerations 143

4.4 Signal Processing 144

4.5 Detection of Explosives 148

4.6 Land-Mine Detection 152

4.7 Illicit Drugs 156

4.7.1 Cocaine 157

4.7.2 Cocaine Hydrochloride 157

4.7.3 Heroin (Diamorphine) 158

4.8 Summary 162

5 Radar Systems 164

5.1 Introduction 164

5.2 Doppler Radar Systems 164

5.3 Frequency-Domain Radars 169

5.3.1 Introduction 169

5.3.2 Two-Frequency Doppler Radar 170 5.3.3 Stepped Freque...