Preface ........................................................ xi
Chapter 1
Introduction .................................................... 1
1.1 Security Sensing ........................................... 1
1.1.1 Needs for Remote Security Sensing ................... 1
1.1.2 Advantages of Microwave and Millimeter-Wave
Remote Sensors ...................................... 2
1.2 Overview of Remote Sensing Techniques ...................... 3
1.2.1 Radiometry .......................................... 3
1.2.2 Radar Systems ....................................... 4
1.2.3 Imaging Systems ..................................... 4
1.2.4 Interferometric Angular Velocity Measurement ........ 5
1.2.5 Microwave and Millimeter-Wave Remote Sensing
in Related Fields ................................... 5
1.3 The Microwave and Millimeter-Wave Spectrum ................. 7
1.3.1 Frequency Designations .............................. 7
1.3.2 Propagation of Microwave and Millimeter-Wave
Radiation ........................................... 8
1.4 Examples of Remote Security Sensors ........................ 9
1.4.1 Active Imaging for Contraband Detection ............ 10
1.4.2 Passive Imaging for Contraband Detection ........... 10
1.4.3 Detection of Human Presence ........................ 12
1.4.4 Discrimination of Humans and Classification of
Human Activity ..................................... 18
1.4.5 Through-Wall Detection ............................. 19
1.4.6 Biological Signature Detection ..................... 20
References ................................................ 20
Chapter 2
Electromagnetic Plane Wave Fundamentals ........................ 27
2.1 Maxwell's Equations ....................................... 27
2.1.1 The Constitutive Parameters ........................ 30
2.2 Time-Harmonic Electromagnetic Fields ...................... 31
2.2.1 The Wave Equation .................................. 32
2.2.2 Plane Waves ........................................ 33
2.2.3 Energy and Power ................................... 37
2.3 Wave Polarization ......................................... 38
2.3.1 Linear Polarization ................................ 39
2.3.2 Elliptical Polarization ............................ 40
References ................................................ 42
Chapter 3
Electromagnetic Waves in Media ................................. 43
3.1 Plane Wave Propagation in Unbounded Media ................. 44
3.1.1 Good Conducting Media .............................. 46
3.1.2 Good Dielectric Media .............................. 47
3.1.3 Wave Impedance in Media ............................ 48
3.1.4 Complex Permittivity and Dispersion ................ 48
3.2 Plane Wave Propagation in Bounded Media ................... 51
3.2.1 Reflection and Transmission of Normally Incident
Waves .............................................. 52
3.2.2 Reflection and Transmission of Arbitrarily
Incident Waves ..................................... 54
3.2.3 Power Reflection and Transmission .................. 58
3.2.4 Total Transmission and Total Reflection ............ 60
3.2.5 Layered Media ...................................... 61
3.3 Electromagnetic Propagation in Specific Media ............. 63
3.3.1 Atmospheric Propagation Effects .................... 63
3.3.2 Propagation Through Building Materials ............. 69
3.3.3 Propagation Through Clothing and Garment
Materials .......................................... 70
3.3.4 Dielectric Properties of Explosives, Plastics,
and Metals ......................................... 71
3.3.5 Dielectric Properties of Human Tissue .............. 72
References ................................................ 81
Chapter 4
Antennas ....................................................... 85
4.1 Electromagnetic Potentials ................................ 86
4.1.1 Electromagnetic Potentials Due to Electric
Current Density J .................................. 86
4.1.2 Electromagnetic Potentials Due to Magnetic Current
Density Jm ......................................... 88
4.1.3 Infinitesimal Dipole Radiation ..................... 89
4.1.4 Far Field Radiation ................................ 90
4.1.5 Infinitesimal Dipole Far-Field Radiation ........... 94
4.2 Antenna Parameters ........................................ 95
4.2.1 Radiated Power Density and Total Radiated Power .... 95
4.2.2 Antenna Pattern .................................... 96
4.2.3 Antenna Pattern Beamwidth .......................... 97
4.2.4 Antenna Solid Angles ............................... 99
4.2.5 Directivity ........................................ 99
4.2.6 Gain .............................................. 101
4.2.7 Aperture Area and Pattern Solid Angle ............. 102
4.2.8 Antenna Temperature and Noise Power ............... 103
4.2.9 Polarization ...................................... 103
4.3 Properties of Wire Antennas .............................. 104
4.3.1 Infinitesimal Dipole .............................. 104
4.3.2 Long Dipole ....................................... 105
4.4 Aperture Antennas ........................................ 107
4.4.1 Image theory ...................................... 108
4.4.2 The Equivalence Principle ......................... 109
4.4.3 Radiation from a Rectangular Aperture ............. 111
4.4.4 Radiation from a Circular Aperture ................ 115
4.5 Antenna Arrays ........................................... 117
4.5.1 Linear Array Theory ............................... 118
4.5.2 Planar Arrays ..................................... 121
4.5.3 Array Beamwidth ................................... 122
4.5.4 Phased Arrays ..................................... 123
4.5.5 Array Architectures ............................... 125
4.6 Common Microwave and Millimeter-Wave Antennas ............ 128
4.6.1 Horn Antennas ..................................... 128
4.6.2 Slot Antennas ..................................... 131
4.6.3 Microstrip Antennas ............................... 132
4.6.4 Reflector Antenna Systems ......................... 134
4.6.5 Lens Antenna Systems .............................. 136
References ............................................... 137
Receivers ................................................ 139
5.1 General Operation of Receivers ........................... 140
5.2 Receiver Noise ........................................... 143
5.2.1 Sources of Receiver Noise ......................... 144
5.2.2 Equivalent Noise Bandwidth ........................ 146
5.2.3 Thermal Noise at Millimeter-Wave Frequencies ...... 148
5.3 Noise Figure and Noise Temperature ....................... 150
5.3.1 Noise Figure ...................................... 150
5.3.2 Noise Temperature ................................. 152
5.3.3 Noise Figure of an Attenuator ..................... 153
5.3.4 Noise in Cascaded Systems ......................... 154
5.3.5 ADC Noise ......................................... 157
5.4 Receiver Linearity ....................................... 160
5.4.1 Gain Compression .................................. 162
5.4.2 Intermodulation Products .......................... 164
5.4.3 Third Order Intercept Point ....................... 166
5.4.4 Intercept Point of a Cascade ...................... 168
5.4.5 Dynamic Range ..................................... 168
5.4.6 Spurious Free Dynamic Range ....................... 170
References ............................................... 171
Radiometry ............................................... 173
6.1 Radiometry Fundamentals .................................. 174
6.1.1 Brightness ........................................ 174
6.1.2 Brightness and Distance ........................... 176
6.1.3 Flux Density and Source Distribution .............. 178
6.1.4 Effect of the Antenna ............................. 179
6.2 Blackbody Radiation ...................................... 180
6.2.1 Planck's Blackbody Radiation Law .................. 180
6.2.2 Approximations of Planck's Law .................... 184
6.2.3 Band-Limited Integration of Planck's Law .......... 185
6.3 Applied Radiometry ....................................... 187
6.3.1 Source Resolution ................................. 188
6.3.2 Received Power as a Convolution ................... 190
6.3.3 Emissivity and Radiometric Temperature ............ 191
6.4 Radiometer Receivers ..................................... 196
6.4.1 Sensitivity ....................................... 197
6.4.2 Total Power Radiometer ............................ 200
6.4.3 Interferometric Correlation Radiometer ............ 206
6.5 Practical Considerations ................................. 215
6.5.1 Receiver Instabilities ............................ 215
6.5.2 Dicke Radiometer .................................. 215
6.5.3 Radiometer Calibration ............................ 217
6.6 Scanning Radiometer Systems .............................. 218
6.6.1 Spatial Resolution ................................ 219
6.6.2 Dwell Time ........................................ 222
6.6.3 Measurement Uncertainty ........................... 223
References ............................................... 226
Radar .................................................... 229
7.1 Radar Fundamentals ....................................... 230
7.1.1 Configurations and Measurements ................... 231
7.1.2 Range Equation .................................... 233
7.2 Transmitter Systems ...................................... 236
7.2.1 Transmitter Functionality ......................... 236
7.2.2 Transmitter Noise ................................. 239
7.2.3 Millimeter-Wave Oscillators ....................... 241
7.3 Radar Measurement Sensitivity ............................ 243
7.3.1 Measurement Error ................................. 243
7.3.2 Impact of the Time-Bandwidth Product on
Measurement Error ................................. 251
7.4 Micro-Doppler ............................................ 253
7.4.1 Micro-Doppler in Security Radar ................... 254
7.4.2 Micro-Doppler Theory .............................. 255
7.4.3 Human Micro-Doppler Signature ..................... 260
7.5 Continuous-Wave Radar .................................... 266
7.5.1 Continuous-Wave Doppler ........................... 267
7.5.2 Frequency-Modulated CW ............................ 271
7.5.3 Multifrequency CW ................................. 274
7.5.4 Moving Target Indication Radar .................... 275
7.6 High-Range Resolution Radar .............................. 279
7.6.1 Pulse Radar ....................................... 280
7.6.2 Linear Frequency Modulation ....................... 282
7.6.3 Stepped-Frequency Modulation ...................... 285
References ............................................... 286
CHAPTER 8
Imaging Systems ............................................... 289
8.1 Scanning Imaging Systems ................................. 291
8.1.1 Types of Scanning Imagers ......................... 291
8.1.2 General Characteristics of Scanning Systems ....... 292
8.2 Interferometric Imaging Systems .......................... 295
8.2.1 Introduction ...................................... 295
8.2.2 Image Formation ................................... 296
8.2.3 Visibility Sampling ............................... 303
8.2.4 Two-Dimensional Visibility ........................ 308
8.2.5 Image Sensitivity ................................. 309
8.2.6 Image Resolution and Field of View ................ 312
8.2.7 Interferometric Imaging Arrays .................... 318
References ............................................... 325
CHAPTER 9
Interferometric Measurement of Angular Velocity ............... 329
9.1 Interferometer Response to an Angularly Moving Point
Source ................................................... 330
9.1.1 System Beam Pattern ............................... 331
9.1.2 Frequency Shift Induced by an Angularly Moving
Object ............................................ 332
9.1.3 Comparison to Doppler Frequency Shift ............. 333
9.1.4 Frequency Uncertainty at Wide Angles .............. 335
9.1.5 Small Angle Approximation ......................... 335
9.2 Interferometer Spectral Response ......................... 336
9.2.1 General Spectral Response ......................... 336
9.2.2 Response with a Sine Function System Beam
Pattern ........................................... 337
9.2.3 Interferometer Response in the Time-Frequency
Domain ............................................ 341
9.3 Interferometric Measurement of Moving Humans ............. 344
9.3.1 Narrow-Beamwidth Response to a Moving Human ....... 344
9.3.2 Wide-Beamwidth Response to a Moving Human ......... 346
References ............................................... 349
List of Symbols ............................................... 351
List of Abbreviations and Acronyms ............................ 355
About the Author .............................................. 357
Index ......................................................... 359
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