Radar Target Imaging

204 Pages·1994·15.333 MB·English

by  H. Überall (auth.), W.-M. Boerner, H. Überall (eds.)

Springer Series on
13
Springer Series on
Editors: L. M. Brekhovskikh L. B. Felsen H. A. Haus
Managing Editor: H. K.V. Lotsch
Volume 1 Volume 10
Mechanics of Continua and Acoustics of Layered Media II
Wave Dynamics 2nd Edition Point Sources and Bounded Beams
By L. M. Brekhovskikh, V Goncharov By L.M. Brekhovskikh, O.A. Godin
Volume 2 Volume 11
Rayleigh-Wave Theory and Application Resonance Acoustic Spectroscopy
Editors: E.A. Ash, E.G.S. Paige By N. Veksler
Volume 12
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Scalar Wave Theory
Electromagnetic Surface Excitations
Green's Functions and Applications
Editors: R. F. Wallis, G. 1. Stegeman
By l.A. De Santo
Volume 4 Volume 13
Short-Wavelength Diffraction Theory Radar Target Imaging
Asymptotic Methods Editors: W-M. Boerner, H. Uberall
By VM. Babic, VS. Buldyrev
Volume 14
Volume 5 Random Media and Boundaries
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Plane and Quasi-Plane Waves and Applications
By L.M. Brekhovskikh, O.A. Godin By K. Furutsu
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Recent Developments in Surface
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Volume 9 Evaluation and Application of Mellin
Nonlinear Optics in Solids Transforms
Editor: O. Keller By R.l. Sasiela
W.-M. Boerner . H. Uberall (Eds.)
Radar Target Imaging
With 101 Figures
Springer-Verlag
Berlin Heidelberg New York London Paris
Tokyo Hong Kong Barcelona Budapest
W.-M. Boerner
UIC-EECS/CSL, M/C 154
University of Illinois at Chicago Circle
Chicago, IL 60607-7018, USA
H. Uberall
Department of Physics
The Catholic University of America
Washington, DC 20064, USA
Series Editors:
Professor Leonid M. Brekhovskikh, Academician
P.P. Shirsov Institute of Oceanology, Russian Academy of Sciences, Krasikowa Street 23,
117218 Moscow, Russia
Professor Leopold B. Felsen, Ph.D.
Electrical Engineering Department, Polytechnic University, Six Metrotech Center,
Brooklyn, NY 11201, USA
Professor Hermann A. Haus
Department of Electrical Engineering & Computer Science, MIT,
Cambridge, MA 02139, USA
Managing Editor: Dr.-Ing. Helmut K.V. Lotsch
Springer-Verlag, Tiergartenstraf3e 17,
69121 Heidelberg, Germany
ISBN-13: 978-3-642-85114-8 e-ISBN-13: 978-3-642-85112-4
DOl: 10.1007/978-3-642-85112-4
Library of Congress Cataloging-in-Publication Data. Boerner, Wolfgang M., 1937- . Modern problems in radar
target imaging/Wolfgang-Martin Boerner, Herbert Uberall. p. cm. -(Springer series on wave phenomena; 13).
Includes bibliographical references and index. ISBN 3-540-57791-2 (Berlin: alk. paper). -ISBN 0 387-57791-2
(New York: alk. paper). 1. Radar cross sections. 2. Radar targets. 3. Electromagnetic waves
Polarization. 4. Electromagnetic waves - Scattering. I. Uberall, Herbert, 1931- . II. Title. III. Series.
TK6580.B62 1994 621.3848 dc20 94-8274
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Preface
This book comprises a series of chapters, largely related to each other and
written by several different researchers who are experts on their respective
topics. They treat modern methods applicable to radar target-imaging prob
lems, which have been developed in the last few years. They provide enhanced
understanding of the physical phenomena and detailed, refined approaches to
the analysis of radar echoes that are expected both to help develop more precise
radar imaging techniques, and to influence the design of a new generation of
radar systems. These advanced approaches fall into the general categories of (a)
the solution of the "inverse-scattering problem", i.e., the processing of measured
radar echo signals designed to extract detailed information on target shapes and
properties - this will, in an increasing measure, involve consideration of the
polarization states of the signal; (b) analysis of the resonance features of the
target, determined by the singularities of the radar scattering amplitude as first
pointed out by C. Baum in his Singularity Expansion Method; and (c) develop
ment of modern measurement methods for radar echoes, as exemplified by the
radar range at the ElectroScience Laboratory of Ohio State University. The
presentation of these three groups of modern radar topics, as contained in this
book through its various, related chapters, will serve the reader with a handy
source of access and reference to recent advanced developments in radar
scattering theory and experimental methods, and may lead him to new territory
and further advances in this modern area of research.
April 1994 Wolfang-Martin Boerner
Herbert Uberall
Contents
1 Introduction
By H. Uberall . 1
References . . . 3
2 Radar Polarimetry: Applications to Radar Systems
By D. Giuli (With 29 Figures). . . . . . . . . . . . . 5
2.1 Polarization Behavior of Different Radar Objects. 5
2.2 Some Implementation Aspects . . . . . . . . . . . . 8
2.2.1 Dual-Polarization Radar Configurations. . 9
2.2.2 Polarization Adaptation. . . . . . . . . . . . 10
2.2.3 Radar System Requirements . . . . . . . . . 11
2.3 Optimum Radar Receivers for Target Detection in the Clear . 12
2.3.1 Some Optimum Receiver Structures. . . . . 14
<
2.3.2 Some Remarks on Performance Evaluation 16
2.4 Evaluation of Polarimetric Doppler Resolution
Through Cramer-Rao Bounds. 19
2.4.1 Signal Modeling . . . . . . . . . .... 20
2.4.2 Cramer-Rao Bound
and Maximum Likelihood Estimation 21
2.5 Adaptive Polarization Cancellation
of Partially Polarized Disturbance. . . . . . 29
2.5.1 Improving Signal/Disturbance Ratio
Through Polarization Adaptation . . 29
2.5.2 Polarization Adaptation for Disturbance Cancellation. 33
2.5.3 Results on Adaptive Polarization Cancellation
of Partially Polarized Disturbance. . 38
2.6 Conclusions and Perspectives. 44
References . . . . . . . . . . . . . . . . . . . . . . . 45
3 Fine Resolution of Radar Targets
By H. Uberall (With 34 Figures) . . . . . . . . 47
3.1 Connection Between Creeping Waves
and the Singularity Expansion Method. 47
3.1.1 Watson Transformation. . . . . . 48
3.1.2 Singularity Expansion Method: Conducting Targets. 51
3.1.3 Dielectric Targets. . . . . . . . . . . . . . . . . . . . . . 64
VIII Contents
3.2 Surface Wave Resonances on Smooth Targets
of General Shape. . . . . . . . . . . . . . . . . . . 71
3.2.1 Finite Circular-Cylindrical Cavity. . . . . 72
3.2.2 Resonances of Conducting Finite Cylinders
and Prolate Spheroids . . . . . . . . . . 77
3.2.3 Phase Matching of Surface Waves
on Conducting Spheroids . 85
3.3 Application to Inverse Scattering. . . . 91
3.3.1 Radar Spectroscopy . . . . . . . 93
3.3.2 The Inverse Scattering Problem
for a Coated Conducting Sphere. . . 98
3.3.3 Transient Observation of Resonance Frequencies. 103
3.4 Conclusions 108
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
4 A Unified Theory of Multidimensional Electromagnetic Vector
Inverse Scattering Within the Kirchhoff or Born Approximation
By K.J. Langenberg, M. BrandfaB, P. Fellinger, T. Gurke,
and T. Kreutter (With 17 Figures) . . . . . . . . . . . . . . . . 113
4.1 Integral Representations for Electromagnetic Scattering
by Perfectly Conducting and Dielectric Scatterers. . . . 114
4.2 Linearization in Terms of the Born
or Kirchhoff Approximation for Plane Wave Incidence 118
4.3 Dyadic Backpropagation in Terms of the Generalized Vector
Holographic Fields. . . . . . . . . . . . . . . . . . . . . . . . 119
4.4 Solution of the Linearized Electric Vector Porter-Bojarski
Equation in the Frequency Diversity Mode . . . . . . . . . 121
4.4.1 Dielectric Scatterer Within the Born Approximation. 121
4.4.2 Perfectly Conducting Scatterer
Within the Kirchhoff Approximation. 129
4.5 Numerical Simulations. . . . . . . . . . . . . 136
4.6 Conclusions.................... 146
4.A Some Properties of Singular Functions. . . . 146
4.B Computation of the Generalized Vector Holographic Field
in Terms of the Scattering Amplitude. 149
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
5 The Measurement of Radar Cross Section
By E.K. Walton (With 23 Figures) . . . . . 152
5.1 Measurement Theory. . . . . . . . . . 152
5.1.1 Calibration of Measurements. 153
5.2 The OSU Measurement Range. . . . 155
5.2.1 Compact Range Architecture. 155
5.2.2 Reflector Types and Trade Offs 155
5.2.3 The Feed ............. 157
Contents IX
5.2.4 Test Target Support . . . . . . . . . . . . .... 158
5.2.5 Instrumentation........................ 160
5.2.6 Range Sensitivity . . 161
5.3 Performance Analysis . . . 162
5.3.1 Direction of Arrival 164
5.3.2 Near Field Imaging 172
5.3.3 Conclusions.......... 174
5.4 Analysis of RCS Measurements .................. . 175
5.4.1 Frequency Domain Techniques ............. . 175
5.4.2 Aspect Angle Domain Processing . . . . . . . . 185
References 192
Subject Index. . . 193
Contributors
Brandfaft, M.
University of Kassel, Department of Electrical Engineering, 34109 Kassel,
Germany
Fellinger, P.
University of Kassel, Department of Electrical Engineering, 34109 Kassel,
Germany
Giuli, D.
Universita di Firenze, Dipartimento di Ingegneria Elettronica,
Facolta di Ingegneria, Via S. Marta 3, 50139 Firenze, Italy
Gurke, T.
University of Kassel, Department of Electrical Engineering, 34109 Kassel,
Germany
Kreutter, T.
University of Kassel, Department of Electrical Engineering, 34109 Kassel,
Germany
Langenberg, K.J.
University of Kassel, Department of Electrical Engineering, 34109 Kassel,
Germany
Uberall, H.
The Catholic University of America, Department of Physics, Washington,
DC 20064, USA
Walton, E.K.
The Ohio State University, Electrical Engineering Department,
ElectroScience Laboratory, 1320 Kinnear Road, Columbus,
OR 43212-1191, USA
1 Introduction
H. Uberall
The decisive effect which the British invention of radar (at first called "asdic")
had in the latter part of World War II on the outcome of that war, is very well
known and understood. Military applications have spurred the huge subsequent
development of the radar industry, although civilian radar applications such as
air and sea traffic control, remote sensing, meteorological radar, etc. also had a
large share. Radar targets were detected by their echoes, and their location
was determined from the travel time of a radar pulse. Their trajectory could
be followed along, and the Doppler effect was also used to gauge radial
motion.
The problem of target recognition, going beyond mere target location, is
more difficult by an order of magnitude at least. The unfortunate incident of an
Iranian commercial aircraft being shot down over the Persian Gulf when
mistaken for a fighter plane is striking witness to that. This general problem area
is termed "inverse problem" or, in our particular case, "inverse scattering", when
the detailed properties of a target are to be determined from the received radar
echo returns. One possible approach towards solving this problem was pointed
out by c.E. Baum in 1971 in the "Interaction Note No. 88" of Kirtland Air
Force Base, Albuquerque, NM [Ll]; this was termed the "Singularity Ex
pansion Method", or SEM. It is based on the idea that the complex resonance
frequencies of a target such as an aircraft form a pattern in the complex
frequency plane which is characteristic for the size and form of a given (metallic,
i.e. conducting) aircraft, for example; researchers such as Moffat and Mains at
Ohio State University [1.2], Van Blaricum [1.3], Miller [1.4] and others were
following this up by expanding radar echoes in Prony series, as introduced by
the Baron Prony in 1795 in the Journal of the Ecole Poly technique, Paris [1.5].
This was later extended to dielectric targets, too. A large literature on inverse
problems has developed, cf. the special journal Inverse Problems, being part H of
the British Journal of Physics. This includes radar, microwaves, acoustic signals,
geophysical prospecting and more, and sophisticated mathematical approaches
have been developed as witnessed by the present Chapter 4.
One very important means for inverse radar problem solutions is offered
by the fact that electromagnetic waves carry polarization, as discovered by
Huygens in 1677 [1.6]. In radar, this can, e.g., be utilized to gain better access to
shape determinations of radar targets, as shown as early as 1977 by Chaudhury
and Boerner [1.7]. The first extensive studies of radar polarization per se were
Spnnger Senes on Wave Phenomena, Vol. 13
BoemerjOberall (Eds) Radar Target Imaging
© Springer-Verlag Berlin Heidelberg 1994