1st Edition

Introduction to Microwave Remote Sensing

By Iain H. Woodhouse Copyright 2006
    400 Pages 87 B/W Illustrations
    by CRC Press

    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?


    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 Properties of EM Waves

    Electromagnetic Radiation as Waves
    Complex Wave Description

    Energy and Power of Waves


    Combination of Waves


    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


    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


    Continuous Media and the Atmosphere

    Radiative Transfer Theory
    Microwave Brightness Temperature
    Spectral Lines
    Line Broadening
    Faraday Rotation

    Interaction With Discrete Objects

    Importance of Diffraction
    Radar Cross-section
    Importance of Scattering Theory

    Scattering and Emission from Volumes

    Transmission Through Volumes

    Reflection and Emission from Smooth Surfaces

    Scattering from Smooth Boundaries
    Emission from Smooth Boundaries

    Scattering and Emission from Rough Surfaces

    Definition of “Rough”
    Effects of Roughness

    Non-Random (Periodic) Surfaces

    Scattering and Emission from Natural Surfaces

    Oceans and Lakes
    Ice and Snow
    Freshwater Ice
    Glacial Ice
    Sea Ice
    Bare Rock and Deserts

    Special Scatterers

    Corner Reflectors
    Moving Targets
    Mixed Targets

    Further Reading


    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


    Coherent Systems

    Active Systems

    System Performance

    Noise and Sensitivity
    Sensitivity Considerations for Receivers
    Other Sources of Uncertainty


    Antenna Calibration
    Verification and Validation
    Types of Calibration
    Strategies for Calibrating Receivers

    Final Remarks on Calibration

    Further Reading


    Atmospheric Sounding

    The Need for Measurements
    The Earth’s Atmosphere
    Water Vapour and Oxygen
    Clouds and Precipitation
    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


    Principles of Measurement

    Practical Radiometers
    Viewing Geometries
    The Generic Forward Model


    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


    The Need for Measurements
    The Forward Problem Over Land
    Empirical Approaches to Snow Depth
    A Final Comment on Passive Polarimetry

    Further Reading


    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
    Echo Shape Analysis
    Range Ambiguity
    Accuracy of Height Retrievals
    Scanning Altimeters
    Calibration and Validation

    Improving Directionality

    Sub-Beamwidth Resolution
    Synthetic Aperture Altimeters


    The Need for Scatterometer Measurements
    General Operation
    Rain Radar
    Polarimetric Scatterometers

    Further Reading


    The Need for Imaging Radar

    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

    Coverage vs PRF

    Other SAR Modes

    ScanSAR Operation
    Spotlight Mode

    Working With SAR Images

    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


    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
    Summary of Decorrelation

    Practical DEM Generation

    InSAR Processing Chain

    Vegetation Height Estimation

    Single Frequency
    Polarimetric Interferometry and Multibaseline
    SAR Tomography

    Differential SAR Interferometry

    Considerations and Limitations
    Atmospheric Water Vapour

    Permanent Scatterer Interferometry

    Along-Track Interferometry

    Further Reading

    APPENDIX: Summary of Useful



    Steradian (solid angle)

    Some Useful Trigonometric Relations

    Logs and Exponentials

    Some Fundamental Properties
    Special values
    Series Expansions

    Complex Numbers


    Law of Vector Algebra
    Cross or Vector Product


    Matrix Algebra


    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