Introduction to Microwave Remote Sensing offers an extensive overview of this versatile and extremely precise technology for technically oriented undergraduates and graduate students.
This textbook emphasizes an important shift in conceptualization and directs it toward students with prior knowledge of optical remote sensing: the author dispels any linkage between microwave and optical remote sensing. Instead, he constructs the concept of microwave remote sensing by comparing it to the process of audio perception, explaining the workings of the ear as a metaphor for microwave instrumentation.
This volume takes an “application-driven” approach. Instead of describing the technology and then its uses, this textbook justifies the need for measurement then explains how microwave technology addresses this need.
Following a brief summary of the field and a history of the use of microwaves, the book explores the physical properties of microwaves and the polarimetric properties of electromagnetic waves. It examines the interaction of microwaves with matter, analyzes passive atmospheric and passive surface measurements, and describes the operation of altimeters and scatterometers. The textbook concludes by explaining how high resolution images are created using radars, and how techniques of interferometry can be applied to both passive and active sensors.
Overview of Microwave Systems
Information from Passive Microwave Imagers
Information from Passive Microwave Sounders
Information from Active Microwave Instruments
How Can This Information be Used?
A BRIEF HISTORY OF MICROWAVES
In the Beginning
Out of the Darkness: Maxwell and Hertz
Radios, Death Rays and Radar
The Venus Ruler and Little Green Men
Imaging Radar
Microwave Remote Sensing from Space
Further Reading
PHYSICAL FUNDAMENTALS
Physical Properties of EM Waves
Electromagnetic Radiation as Waves
Complex Wave Description
Energy and Power of Waves
Polarisation
Combination of Waves
Coherence
The Most Important Section in This Book
Phase as a (Relative) Distance Measure
Combining Two Waves in 2-D
Quantifying the Interference Pattern
Passive Case
Multiple Source Interference Pattern
Beamwidth and Angular Resolution
Huygens’ Wavelets
More on Coherence
Propagation of Microwaves
Through Lossy Media
Moving Sources
Where Do Microwaves Come From?
How Are They Produced in Nature?
Radiation Laws
How Are Microwaves Produced Artificially?
Further Reading
POLARIMETRY
Describing Polarised Waves
Summary of Linear Basis
Superposition of Polarised Waves
Representing Polarisation
Poincaré sphere
Mathematical Description
Stokes Vector
Brightness Stokes Vector
Partially Polarised Waves
The Stokes Scattering Matrix
The Scattering Matrix
Target Vector
Covariance Matrix
Passive Polarimetry
Polarimetry in Radar
Radar Polarimeters
Polarimetric Synthesis and Response Curves
Important Polarimetric Properties
Unpolarised Power
Degree of Polarisation and Coefficient of Variation
Polarimetric Ratios
Coherent Parameters
Polarimetric Decomposition
Further Reading
MICROWAVES IN THE REAL WORLD
Continuous Media and the Atmosphere
Radiative Transfer Theory
Microwave Brightness Temperature
Spectral Lines
Line Broadening
Faraday Rotation
Interaction With Discrete Objects
Diffraction
Importance of Diffraction
Scattering
Radar Cross-section
Importance of Scattering Theory
Scattering and Emission from Volumes
Transmission Through Volumes
Emission
Scattering
Reflection and Emission from Smooth Surfaces
Scattering from Smooth Boundaries
Emission from Smooth Boundaries
Summary
Scattering and Emission from Rough Surfaces
Definition of “Rough”
Effects of Roughness
Summary
Non-Random (Periodic) Surfaces
Scattering and Emission from Natural Surfaces
Oceans and Lakes
Hydrometeors
Ice and Snow
Freshwater Ice
Glacial Ice
Sea Ice
Bare Rock and Deserts
Soils
Vegetation
Special Scatterers
Corner Reflectors
Moving Targets
Mixed Targets
Further Reading
DETECTING MICROWAVES
General Approach
Conceptual Approach to Microwave Systems
A Word of Warning
Basic Microwave Radiometer
The Antenna
Parabolic Antennas
The Dipole Antenna
Array Antennas
Antenna Properties
The Receiver
Detector
Coherent Systems
Active Systems
System Performance
Noise and Sensitivity
Sensitivity Considerations for Receivers
Other Sources of Uncertainty
Calibration
Antenna Calibration
Verification and Validation
Types of Calibration
Strategies for Calibrating Receivers
Final Remarks on Calibration
Further Reading
ATMOSPHERIC SOUNDING
Atmospheric Sounding
The Need for Measurements
The Earth’s Atmosphere
Water Vapour and Oxygen
Clouds and Precipitation
Ozone
Chlorine Monoxide
Other Relevant Measurements
Principles of Measurement
Theoretical Basis of Sounding
The Forward Model
Simple Formulation of the Forward Model
The Inverse Model
Solving the Inverse Problem
The Influence Functions
Viewing Geometries
Nadir Sounding
Limb Sounding
Passive Rainfall Mapping
The Need for Measurements
Principles of Measurement
Emission Method
Scattering Method
Further Reading
PASSIVE IMAGING
Principles of Measurement
Background
Practical Radiometers
Viewing Geometries
The Generic Forward Model
Oceans
The Need for Measurements
Principles of Measurement: SST
Principles of Measurement: Ocean Salinity
Principles of Measurement: Ocean Winds
Sea Ice
The Need for Measurements
Sea Ice Concentration
Land
The Need for Measurements
The Forward Problem Over Land
Empirical Approaches to Snow Depth
A Final Comment on Passive Polarimetry
Further Reading
ACTIVE MICROWAVES
Principles of Measurement
What is RADAR?
Basic Radar Operation
The Generic Equations of Radar Performance
The Radar Equation
Range resolution
Radar Altimeters
The Need for Altimeter Measurements
Altimeter Geometry
Instrumentation
Echo Shape Analysis
Range Ambiguity
Accuracy of Height Retrievals
Scanning Altimeters
Calibration and Validation
Improving Directionality
Sub-Beamwidth Resolution
Synthetic Aperture Altimeters
Scatterometers
The Need for Scatterometer Measurements
General Operation
Rain Radar
Windscatterometers
Polarimetric Scatterometers
Further Reading
IMAGING RADAR
The Need for Imaging Radar
Oceans
Sea Ice
Terrestrial Surfaces
The Water Cloud Model for Vegetation
Other Uses of Radar Imagery
What is an Image?
Radar Image Construction
Side-Looking Airborne Radar
Ground Range resolution
Azimuth Resolution
Synthetic Aperture Radar (SAR)
Aperture Synthesis: A Doppler Interpretation
Aperture Synthesis: A Geometric Explanation
Geometry vs. Doppler
SAR Focussing
Radar Equation for SAR
Geometric Distortions in Radar Images
Lay-over and Foreshortening
Radar Shadow
Motion Errors
Moving Targets
Operational Limits
Ambiguities
Coverage vs PRF
Other SAR Modes
ScanSAR Operation
Spotlight Mode
Working With SAR Images
Speckle
Speckle Statistics
Speckle Filtering
Geometric Correction
Limitations of Geometric Correction
SAR Data Formats
Extracting Topography from SAR Images
Stereo SAR Radargrammetry
SAR Clinometry
Further Reading
INTERFEROMETRY
The Need for Interferometric Measurements
Principles of Interferometry
Phase Measurements
Application of Dual Systems
Interferometry for Resolving Direction
Passive Imaging Interferometry
Radar Interferometry
Interferometric Altimetry
Interferometric SAR
InSAR Viewing Geometries
Interferometric Coherence Magnitude
Decorrelation
Summary of Decorrelation
Practical DEM Generation
InSAR Processing Chain
Vegetation Height Estimation
Single Frequency
Dual-Frequency
Polarimetric Interferometry and Multibaseline
Interferometry
SAR Tomography
Differential SAR Interferometry
Considerations and Limitations
Atmospheric Water Vapour
Permanent Scatterer Interferometry
Along-Track Interferometry
Further Reading
APPENDIX: Summary of Useful
Mathematics
Angles
Degrees
Radians
Steradian (solid angle)
Some Useful Trigonometric Relations
Logs and Exponentials
Some Fundamental Properties
Special values
Series Expansions
Complex Numbers
Vectors
Law of Vector Algebra
Cross or Vector Product
Matrices
Matrix Algebra
Biography
Woodhouse, Iain H.
“This book can serve as a textbook for graduate students on the properties of microwaves and how they can be used to study the Earth, and also as a good reference for remote sensing scientists and engineers who would like a convenient summary of relevant electromagnetic gathered in a single volume. … This book fills an important niche between classical electromagnetic textbooks and detailed application manuals, giving an appreciation of how microwave remote sensing relates discipline science to the fundamentals of radio wave propagation. … The book stands out as a worthy general text that is ideally suited for introductory coursework o tot serve as an advanced reference. This book should find its way onto many desks and bookshelves belonging to remote sensing professionals and future remote sensing professionals.”
—In PE&RS, Vol. 73, No. 7, July 2007