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Remote Sensing with Imaging Radar

:	John A. Richards
:	Remote Sensing with Imaging Radar
:	Springer-Verlag
:	9783642020209
:	1
:	CHF 135.30
:

:	Elektronik, Elektrotechnik, Nachrichtentechnik
:	English

:	361
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

This book is concerned with remote sensing based on the technology of imaging radar. It assumes no prior knowledge of radar on the part of the reader, commencing with a treatment of the essential concepts of microwave imaging and progressing through to the development of multipolarisation and interferometric radar, modes which underpin contemporary applications of the technology. The use of radar for imaging the earth's surface and its resources is not recent. Aircraft-based microwave systems were operating in the 1960s, ahead of optical systems that image in the visible and infrared regions of the spectrum. Optical remote sensing was given a strong impetus with the launch of the first of the Landsat series of satellites in the mid 1970s. Although the Seasat satellite launched in the same era (1978) carried an imaging radar, it operated only for about 12 months and there were not nearly so many microwave systems as optical platforms in service during the 1980s. As a result, the remote sensing community globally tended to develop strongly around optical imaging until Shuttle missions in the early to mid 1980s and free-flying imaging radar satellites in the early to mid 1990s became available, along with several sophisticated aircraft platforms. Since then, and particularly with the unique capabilities and flexibility of imaging radar, there has been an enormous surge of interest in microwave imaging technology. Unlike optical imaging, understanding the theoretical underpinnings of imaging radar can be challenging, particularly when new to the field.

	Preface	6
	TABLE OF CONTENTS	8
	LIST OF SYMBOLS AND OPERATORS	13
	Operators and mathematical conventions	19
	CHAPTER 1 THE IMAGING RADAR SYSTEM	20
	1.1 Why Microwaves?	20
	1.2 Imaging with Microwaves	20
	1.3 Components of an Imaging Radar System	22
	1.4 Assumed Knowledge	24
	1.4.1 Complex Numbers	25
	1.4.2 Vectors and Matrices	25
	1.4.3 Differential Calculus	25
	1.5 Referencing and Footnotes	25
	1.6 A Critical Bibliography	25
	1.7 How this Book is Organised	28
	CHAPTER 2 THE RADIATION FRAMEWORK	30
	2.1 Energy Sources in Remote Sensing	30
	2.2 Wavelength Ranges used in Remote Sensing	33
	2.3 Total Available Energy	34
	2.4 Energy Available for Microwave Imaging	36
	2.5 Passive Microwave Remote Sensing	38
	2.6 The Atmosphere at Microwave Frequencies	38
	2.7 The Benefits of Radar Remote Sensing	40
	2.8 Looking at the Underlying Electromagnetic Fields	41
	2.9 The Concept of Near and Far Fields	45
	2.10 Polarisation	47
	2.11 The Jones Vector	52
	2.12 Circular Polarisation as a Basis Vector System	55
	2.13 The Stokes Parameters, the Stokes Vector and the Modified Stokes Vector	57
	2.14 Unpolarised and Partially Polarised Radiation	59
	2.15 The Poincaré Sphere	61
	2.16 Transmitting and Receiving Polarised Radiation	63
	2.17 Interference	67
	2.18 The Doppler Effect	68
	CHAPTER 3 THE TECHNOLOGY OF RADAR IMAGING	72
	PART A: THE SYSTEM	72
	3.1 Radar as a Remote Sensing Technology	72
	3.2 Range Resolution	74
	3.3 Pulse Compression Radar	77
	3.4 Resolution in the Along Track Direction	80
	3.5 Synthetic Aperture Radar (SAR)	80
	3.6 The Mathematical Basis for SAR	81
	3.7 Swath Width and Bounds on Pulse Repetition Frequency	85
	3.8 The Radar Resolution Cell	87
	3.9 ScanSAR	87
	3.10 Squint and the Spotlight Operating Mode	90
	PART B: THE TARGET	94
	3.11 The Radar Equation	94
	3.12 Theoretical Expression for Radar Cross Section	96
	3.13 The Radar Cross Section in dB	96
	3.14 Distributed Targets	97
	3.15 The Scattering Coefficient in dB	98
	3.16 Polarisation Dependence of the Scattering Coefficient	99
	3.17 The Scattering Matrix	100
	3.18 Target Vectors	104
	3.19 The Covariance and Coherency Matrices	105
	3.20 Measuring the Scattering Matrix	108
	3.21 Relating the Scattering Matrix to the Stokes Vector	109
	3.22 Polarisation Synthesis	111
	3.23 Compact Polarimetry	122
	3.24 Faraday Rotation	125
	CHAPTER 4 CORRECTING AND CALIBRATING RADAR IMAGERY	128
	4.1 Sources of Geometric Distortion	128
	4.1.1 Near Range Compressional Distortion	128
	4.1.2 Layover, Relief Displacement, Foreshortening and Shadowing	130
	4.1.3 Slant Range Imagery	132
	4.2 Geometric Correction of Radar Imagery	134
	4.2.1 Regions of Low Relief	134
	4.2.2 Passive Radar Calibrators	135
	4.2.3 Active Radar Calibrators (ARCs)	136
	4.2.4 Polarimetric Active Radar Calibrators (PARCs)	137
	4.2.5 Regions of High Relief	137
	4.3 Radiometric Correction of Radar Imagery	139
	4.3.1 Speckle	139
	4.3.2 Radar Image Products	146
	4.3.3 Speckle Filtering	147
	4.3.4 Antenna Induced Radiometric Distortion	152
	CHAPTER 5 SCATTERING FROM EARTH SURFACE FEATURES	154
	5.1 Introduction	154
	5.2 Common Scattering Mechanisms	154
	5.3 Surface Scattering	155
	5.3.1 Smooth Surfaces	155
	5.3.2 Rough Surfaces	158
	5.3.3 Penetration into Surface Materials	167
	5.4 Volume Scattering	172
	5.4.1 Modelling Volume Scattering	172
	5.4.2 Depolarisation in Volume Scattering	177
	5.4.3 Extinction in Volume Scattering	178
	5.5 Scattering from Hard Targets	179
	5.5.1 Facet Scattering	180
	5.5.2 Dihedral Corner Reflector Behaviour	181
	5.5.3 Metallic and Resonant Elements	186
	5.5.4 Bragg Scattering	189
	5.5.5 The Cardinal Effect	190
	5.6 Composite Scatterers	191
	5.7 Sea Surface Scattering	191
	5.8 Internal (Ocean) Waves	197
	5.9 Sea Ice Scattering	197
	CHAPTER 6 INTERFEROMETRIC AND TOMOGRAPHIC SAR	200
	6.1 Introduction	200
	6.2 The Importance of Phase	200
	6.3 A Radar Interferometer - InSAR	202
	6.4 Creating the Interferometric Image	204
	6.5 Correcting for Flat Earth Phase Variations	205
	6.6 The Problem with Phase Angle	206
	6.7 Phase Unwrapping	208
	6.8 An Inclined Baseline	209
	6.9 Standard and Ping Pong Modes of Operation	210
	6.10 Types of SAR Interferometry	211
	6.11 The Concept of Critical Baseline	213
	6.12 Decorrelation	215
	6.13 Detecting Topographic Change: Along Track Interferometry	217
	6.14 Polarimetric Interferometric SAR (PolInSAR)	221
	6.14.1 Fundamental Concepts	221
	6.14.2 The T6 Coherency Matrix	225
	6.14.3 Maximising Coherence	226
	6.14.4 The Plot of Complex Coherence	227
	6.15 Tomographic SAR	228
	6.15.1 The Aperture Synthesis Approach	228
	6.15.2 The Fourier Transformation Approach to Vertical Resolution	234
	6.15.3 Unevenly Spaced Fli