Microwave radiometers are tools used for passive microwave remote sensing - a technological process that allows for the measurement of important parameters that help professionals understand and predict climate and weather patterns. Written by leading experts in industry and academia, this authoritative resource offers practitioners a solid understanding of radiometer systems and explains how to design a system based on given specifications, taking into account both technical aspects and geophysical realities. This second edition has been thoroughly updated to reflect the numerous advances that have been made in the field since the original edition was published in 1989. New material covered includes two of today's hottest microwave radiometry topics - polarimetric measurements and aperture synthesis.
Author(s): Niels Skou, David M. Le Vine
Edition: 2
Year: 2006
Language: English
Pages: 250
Microwave Radiometer Systems
Design and Analysis
Second Edition......Page 2
Contents......Page 6
Preface xi......Page 12
1 Introduction 1......Page 13
2 Summary 3......Page 15
3.2 The Sensitivity of the Radiometer 7......Page 19
3.3 Absolute Accuracy and Stability 9......Page 21
4.1 The Total Power Radiometer (TPR) 13......Page 24
4.2 The Dicke Radiometer (DR) 14......Page 25
4.3 The Noise-Injection Radiometer (NIR) 16......Page 27
4.4 The Correlation Radiometer (CORRAD) 18......Page 29
4.5 Hybrid Radiometer 20......Page 31
4.6 Other Radiometer Types 21......Page 32
5.1.1 Direct or Superheterodyne 25......Page 35
5.1.2 DSB or SSB with or without RF Preamplifier 26......Page 36
5.2.1 Microwave Part 27......Page 37
5.2.2 The Noise Figure and the Sensitivity of the Radiometer 29......Page 39
5.2.3 The IF Circuitry and the Detector 30......Page 40
5.2.4 The Extreme Signal Levels 32......Page 42
5.2.5 The LF Circuitry 33......Page 43
5.2.6 The Analog-to-Digital Converter 34......Page 44
5.2.7 On the Sampling in the Radiometer: Aliasing 37......Page 47
5.3 The Noise-Injection Radiometer 38......Page 48
5.4.1 DSB Receiver without RF Preamplifier 40......Page 50
5.4.2 SSB Receiver with RF Preamplifier 42......Page 52
5.5 Stability Considerations 43......Page 53
6 The DTU Noise-Injection Radiometers Example 47......Page 56
7.1 Polarimetry and Stokes Parameters 55......Page 63
7.3.1 Polarization Combining Radiometers 57......Page 65
7.3.2 Correlation Radiometers 60......Page 68
7.4 Sensitivities 62......Page 70
7.6 The DTU Polarimetric System 64......Page 72
8.1 Introduction 69......Page 77
8.2.1 RF Processing 72......Page 80
8.2.2 Basic Equation 73......Page 81
8.2.3 Image Processing 74......Page 82
8.2.4 Sensitivity 75......Page 83
8.3 Example 76......Page 84
9.1 Why Calibrate? 81......Page 88
9.2 Calibration Sources 82......Page 89
9.3 Example: Calibration of a 5-GHz Radiometer 86......Page 93
9.4 Linearity Measured by Simple Means 87......Page 94
9.4.1 Background 88......Page 95
9.4.2 Simple Three-Point Calibration 89......Page 96
9.4.3 Linearity Checked by Slope Measurements 92......Page 99
9.4.4 Measurements 93......Page 100
9.5 Calibration of Polarimetric Radiometers 96......Page 103
10.1 Background 99......Page 106
10.2 The Radiometers Used in the Experiments 100......Page 107
10.3 The Experimental Setup 101......Page 108
10.4 5-GHz Sensitivity Measurements 102......Page 109
10.5.1 Discussion of the 5-GHz DR Results 103......Page 110
10.5.2 The 5-GHz DR with Correction Algorithm 105......Page 112
10.5.3 The 17-GHz NIR Results 109......Page 116
10.5.4 Discussion of the TPR Results 111......Page 118
10.5.5 Back-End Stability 113......Page 120
10.6 Conclusions 114......Page 121
11.1 Beam Efficiency and Losses 117......Page 123
11.2 Antenna Types 119......Page 125
11.3 Imaging Considerations 121......Page 127
11.4 The Dwell Time Per Footprint Versus the Sampling Time in the Radiometer 125......Page 131
11.5 Receiver Considerations for Imagers 130......Page 136
12 Relationships Between Swath Width, Footprint, Integration Time, Sensitivity, Frequency, and Other Parameters for Satellite-Borne, Real Aperture Imaging Systems 133......Page 138
12.1 Mechanical Scan 134......Page 139
12.2 Push-Broom Systems 139......Page 144
12.3 Summary and Discussion 140......Page 145
12.4.2 Coastal Salinity Sensor 143......Page 148
12.4.3 Realistic Salinity Sensor 144......Page 149
13.1 Background 147......Page 151
13.2.1 General Geometric and Radiometric Characteristics 149......Page 153
13.2.2 Instrument Options 152......Page 156
13.2.4 Instrument Layout and Receiver Type 156......Page 160
13.3.1 The Direct Receivers (10.65–36.5 GHz) 157......Page 161
13.3.2 The 89-GHz DSB Receivers 158......Page 162
13.3.3 Integrated Receivers: Weight and Power 159......Page 163
13.3.4 Performance of the Receivers 160......Page 164
13.3.5 Critical Design Features 161......Page 165
13.4 Antenna Design 163......Page 167
13.5.1 Prelaunch Radiometric Calibration 165......Page 169
13.5.2 On-Board Calibration 166......Page 170
13.6.1 System Weight and Power 167......Page 171
13.6.2 Data Rate 168......Page 172
13.7 Summary 169......Page 173
14.1 Background 171......Page 175
14.2 The Brightness Temperature of the Sea 172......Page 176
14.3 The Brightness Temperature of Moist Soil 175......Page 179
14.5.1 Sensitivity Considerations 177......Page 181
14.5.2 The 1.4-GHz Noise-Injection Radiometer Receiver 178......Page 182
14.5.4 Layout of the System 181......Page 185
14.6 Calibration 184......Page 188
14.7.1 The Faraday Rotation 186......Page 190
14.7.2 Correction Based on Knowing the Rotation Angle 187......Page 191
14.7.3 Correction Based on the Polarization Ratio 189......Page 193
14.7.5 Circumventing the Problem by Using the First Stokes Parameter 191......Page 195
14.8.1 Space Radiation 192......Page 196
14.9 Summary 193......Page 197
15.1 Introduction 197......Page 201
15.2 Implementation of Synthesis 198......Page 202
15.3.1 Hardware 200......Page 204
15.3.2 Image Reconstruction 204......Page 208
15.3.3 Calibration 205......Page 209
15.3.4 Discussion 207......Page 211
15.3.5 Example of Imagery 208......Page 212
15.4.1 HYDROSTAR 211......Page 215
15.4.2 SMOS 214......Page 218
Acronyms 219......Page 223
