Radar Reflectivity of Land and Sea / Edition 2

by Maurice W. Long

Overview

This state-of-the-art edition of a radar classic brings you up-to-date on new developments in clutter measurement and modeling and features a wealth of new information not found in other currently available books. Authored by a recognized expert in the field, the book covers everything from basic concepts of radar reflectivity to space-time clutter amplitude and bistatic clutter.

New radar engineers will find this to be a valuable, all-encompassing, well-illustrated survey of radar relectivity fundamentals. Veteran engineers and systems designers will appreciate the book's new coverage of: effects of frequency agility, spatial averages for terrain, graphs from GIT clutter models, land and sea echo at extremely low grazing angles, compound statistics including the K and the Rayleigh modulated by Wiebull distributions, super sea echo events and sea spikes, bistatic land and sea clutter, and more.

Product Details

ISBN-13:	9780890061305
Publisher:	Artech House, Incorporated
Publication date:	01/01/1983
Series:	Radar Library Series
Edition description:	2nd ed
Pages:	424
Product dimensions:	6.00(w) x 9.00(h) x 1.06(d)

Table of Contents

	Preface	xv
	References	xviii
	Acknowledgments	xxi
1	Remote Sensing by Radar	1
1.1	State of the Art	1
1.1.1	Overview	1
1.1.2	Radar Capabilities at the End of World War II	6
1.1.3	Strip Maps and Side-Looking Radar	13
1.1.4	Spaceborne Radar	16
1.2	Surface Effects and Emerging Techniques	21
1.2.1	Effects of Surface Characteristics	21
1.2.2	Modern Techniques for Sensing Surface Characteristics	32
	References	39
2	Basic Concepts and Definitions	43
2.1	Radar Reflectivity	43
2.1.1	The Radar Equation for Free Space	44
2.1.2	Radar Cross Section of Targets	47
2.1.3	Normalized Radar Cross Section	48
2.1.4	Coherence and Incoherence of a Scattered Field	50
2.1.5	Rayleigh Roughness Criterion, Specular Reflection, and Scattering	51
2.1.6	Far Field of Radar Targets	56
2.1.7	Effects of Radar Frequency Changes	57
2.1.8	Echo Fluctuations	58
2.2	The Earth and Its Effects on Radar	59
2.2.1	Effects of the Earth's Curvature and Refraction	59
2.2.2	The Effect of Interference on a Target	63
2.2.3	Nature of the Sea Surface and Wind Speed Statistics	66
2.2.4	Propagation over the Horizon	70
2.2.5	Attenuation and Scattering by the Atmosphere	73
	References	75
3	Polarization, Depolarization, and Theories of Scattering	79
3.1	Polarization and Depolarization	79
3.1.1	Polarization Scattering Matrix	79
3.1.2	Relationships Between Linear and Circular Polarizations	82
3.1.3	A Randomly Oriented Dipole	85
3.1.4	A Dihedral Reflector	87
3.1.5	Depolarization Caused by an Ensemble of Randomly Oriented Dipoles	88
3.2	Theories for Radar Cross Section of Rough Surfaces	91
3.2.1	Simple Models Including the Constant Gamma Model	91
3.2.2	Classical Interference Theory	96
3.2.3	The Tangent Plane Approximation	97
3.2.4	Very Rough Surfaces	97
3.2.5	The Facet Model	98
3.2.6	The Slightly Rough Planar Surface	98
3.2.7	Ripples on Water	100
3.2.8	Vegetation Model	101
3.2.9	Composite Surfaces	103
3.2.10	Doppler Spectra of Sea Echo	104
	References	106
4	Effects of the Earth's Surface	111
4.1	Fundamental Concepts	111
4.1.1	Effects of the Earth's Curvature and Refraction	112
4.1.2	Reflections from a Rough, Spherical Earth	115
4.1.3	Reflection Coefficient for a Flat, Smooth Earth	118
4.1.4	Effect of a Flat, Smooth Earth on Target Echo	125
4.2	Echo from Targets That Are Above a Flat, Smooth Earth	129
4.2.1	Range and Depression Angle Dependencies for a Small Object Above a Smooth Earth	129
4.2.2	Vertically Extensive Objects Above a Smooth Earth	132
4.2.3	Propagation Factors for Circular, Horizontal, and Vertical Polarizations Above a Smooth Earth	135
4.2.4	Propagation Factors for a Cloud of Scatterers Above a Smooth Earth	138
4.3	Effects of Surface Roughness on Forward-Scattered Fields	140
4.3.1	Reflection Coefficient for Rough Surfaces	140
4.3.2	Shadowing	145
4.3.3	Depolarization	146
4.4	Echo from Targets That Are Above a Physically Rough Earth	147
4.4.1	Variation of Echo Power with Range	148
4.4.2	Range at Which Idealized R[superscript -4] and R[superscript -8] Curves Intersect	150
4.4.3	Relative Cross Sections for Circular Polarizations	150
4.4.4	A Cloud of Scatterers	152
4.4.5	Effects of the Diffuse Component on Target Echo	154
4.5	Multipath Effects on Echo from Land and Sea	156
4.5.1	Effects of Multipath Interference	157
4.5.2	Multipath Interference and Shadowing	158
	References	159
5	Echo Fluctuations and Spectra	163
5.1	Introduction	163
5.1.1	Spectra and Autocorrelation Functions	163
5.1.2	Amplitude Statistics	165
5.2	Ground Echo Fluctuations	172
5.2.1	Nature of Ground Echoes	172
5.2.2	Temporal Amplitude Distributions for Terrain	175
5.2.3	Spatial Amplitude Statistics	182
5.2.4	Noncoherent Spectra and Autocorrelation Functions of Land	192
5.2.5	Coherent Land Doppler Spectra	203
5.2.6	Lincoln Laboratory Spectral Model	211
5.2.7	Power in Fast and Slow Land Spectra	213
5.2.8	Bragg Spectra from Inland Water	214
5.2.9	Concluding Remarks on Ground Echo Fluctuations	216
5.3	Visual Observations of Sea Echo	219
5.3.1	Characteristics Revealed by an A-Scope Display	219
5.3.2	Results from Fixed Range Sampling	221
5.3.3	Subjective Radar/Optical Comparisons and Anomalies	224
5.3.4	Observations of Bishop and of Lewis and Olin	225
5.4	Sea Echo Statistics and Spectra	228
5.4.1	Amplitude Distributions	229
5.4.2	Spectra Observed with Noncoherent Radar	241
5.4.3	Autocorrelation Functions	242
5.4.4	Noncoherent Spectra and Relationships with Sea Surface Mechanisms	248
5.4.5	Relative Power in Fast and Slow Fluctuations	250
5.4.6	Phase Coherent Doppler Spectra	254
5.4.7	Super Events	267
5.4.8	Sea Spikes	268
5.4.9	Concluding Remarks on Sea Echo Fluctuations and Spectra	274
5.5	Space-Time Clutter Amplitude Statistics	277
5.5.1	Compound Distributions	277
5.5.2	The K-Distribution	279
5.5.3	Rayleigh Modulated by Weibull Statistics	281
	References	283
6	Average and Median Cross Sections	291
6.1	Introduction	291
6.1.1	General Characteristics of [sigma degree]	292
6.1.2	Differences Between Average and Median Values	294
6.1.3	Smooth Surfaces and Small Grazing Angles	295
6.1.4	Classical Interference Effect	299
6.1.5	Problems Associated with Measuring [sigma degree]	301
6.2	Radar Cross Section for Land	303
6.2.1	Nature of [sigma degree] for Land	303
6.2.2	Sample [sigma degree] Land Measurements	303
6.2.3	Terrain Within Near Vertical and Plateau Regions	332
6.2.4	Ulaby and Dobson Tables for Terrain	336
6.2.5	Terrain Within Plateau and Low Grazing Angle Regions	340
6.2.6	Terrain at Extremely Low Grazing Angles	345
6.2.7	Concluding Remarks on Average Land Echo	350
6.3	Radar Cross Section for the Sea	352
6.3.1	Nature of [sigma degree] for the Sea	352
6.3.2	Range Dependence at Small Grazing Angles	354
6.3.3	Dependence on Grazing Angle	358
6.3.4	Grazing Angle Dependence at Low Frequencies	366
6.3.5	Nathanson Sea Clutter Tables	372
6.3.6	Extremely Low Grazing Angles	374
6.3.7	Dependence of [sigma degree] on Polarization	382
6.3.8	Dependence of [sigma degree] on the Wind and Sea	384
6.3.9	GIT Sea Clutter Models	399
6.3.10	Wavelength Dependence for the Sea	409
6.3.11	A Two-Scatterer Sea Clutter Model	420
6.3.12	Oil Slicks and Rain on Water	424
6.3.13	Concluding Remarks on Average Sea Echo	425
	References	427
7	Interdependence of Polarization Characteristics	435
7.1	Introduction	435
7.1.1	General Observations	435
7.1.2	Coherency, Statistical Independence, and Correlation	437
7.1.3	A Simplified Polarization Model for Rough Terrain	441
7.1.4	Use of the Polarization Model for the Moon	444
7.1.5	Polarization Model with Different Propagation Factors	450
7.2	Echo from Land, Principally Trees	451
7.2.1	Amplitude Fluctuations	452
7.2.2	Interdependence of Amplitude and Phase of Orthogonally Polarized Echoes	453
7.2.3	Average and Median Value Data, and Depression Angle Dependence	455
7.2.4	Relative Magnitude of Coherent and Incoherent Scattering from Trees	459
7.3	Sea Echo	463
7.3.1	Fluctuations of Orthogonally Polarized Components	463
7.3.2	Averages and Medians for Linear Polarization	468
7.3.3	Interdependence of Averages and Medians for Linear and Circular Polarizations	471
7.3.4	Coherent and Incoherent Scattering from the Sea	479
	References	480
8	Bistatic Land and Sea Clutter	483
8.1	Bistatic RCS	483
8.2	Effective Illuminated Area	485
8.3	Depolarization and Reduction in RCS	487
8.4	In-Plane ([phis] = 0 and 180[degree]) Clutter	488
8.5	The Barton Model	490
8.6	Ulaby et al. Indoor Measurements	493
8.7	Out-of-Plane, Small Grazing Angle Data	499
	References	502
Appendix	Statistical Parameters	505
A.1	Basics	505
A.2	Probability Density Functions and Distributions	507
A.2.1	Normal or Gaussian Distribution	507
A.2.2	Rayleigh Distribution	507
A.2.3	Ricean Distribution	508
A.2.4	Lognormal Distribution	509
A.2.5	Weibull Distribution	510
A.2.6	Chi-Square, Gamma, and Weinstock Distributions	511
A.3	Standard Deviation of 10 log [sigma] When [sigma] Is Rayleigh Power Distributed	511
A.4	Relationship Between 10 log([characters not reproducible]igma]/[sigma subscript m]) and Its Variance When [sigma] Is Lognormal	513
	References	514
	About the Author	515
	Index	517