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\. of the International Union of Radio Science NATIONAL ACADEMIES OF SCIENCES AND ENGINEERING NATIONAL RESEARCH COUNCIL \. of the UNITED STATES OF AMERICA UNITED STATES NATIONAL COMMITTEE International Union of Radio Science National Radio Science Meeting 4-8 January 1999 Sponsored by USNC/URSI University of Colorado Boulder, Colorado U.S.A. NOTE: Programs and Abstracts of the USNC/URSI Meetings are available from: USNC/URSI National Academy of Sciences 2101 Constitution Avenue, N.W. Washington, DC 20418 at $5 for 1983-1998 meetings. The full papers are not published in any collected format; requests for them should be addressed to the authors who may have them published on their own initiative. Please note that these meetings are national. They are not organized by the International Union, nor are the programs available from the International Secretariat. ii MEMBERSHIP United States National Committee INTERNATIONAL UNION OF RADIO SCIENCE Chair: Susan K. Avery* Vice Chair: vacant Secretary: Gary Brown Immediate Past Chair: David C. Chang* Members Representing Societies, Groups, and Institutes: American Astronomical Society T.J. Phillips American Geophysical Union George C. Reid American Meteorological Society vacant IEEE Geosciences and Remote Sensing Society Roger Lang IEEE Microwave Theory and Techniques Society Arthur A. Oliner Members-at-Large: Albin Gasiewski John D. Mathews Ronald Pogorzelski Fritz Schuermeyer W. Ross Stone Jill Tarter Roland T. Tsunoda Edgeworth R. Westwater Chairs of the USNC/URSI Commissions: Commission A John D. Norgard Commission B Donald R. Wilton Commission C David Thomson Commission D Robert Mattauch Commission E David). Cohen Commission F Wolfhard Vogel Commission G Lewis Duncan Commission H Umranlnan Commission J Donald Backer Commission K JamesC. Lin Officers, Chairs and Vice Chairs of Commissions of URS! residing in the United States: President Thomas B. A. Senior Chair, Commission A Motohisa Kanda Vice Chair, Commission B Chalmers Butler Chair, Commission G B. W. Reinisch Vice Chair, Commission K J.C.Lin * Member of USNC/URSI Executive Committee iii DESCRIPTION OF THE INTERNATIONAL UNION OF RADIO SCIENCE The International Union of Radio Science is one of the world scientific unions organized under the International Council of Scientific Unions (!CSU). It is commonly designated as URS! (from its French name, Union Radio Scientifique Internationale). Its aims are (1) to promote the scientific study of radio communications, (2) to aid and organize radio research requiring cooperation on an international scale and to encourage the discussion and publication of the results, (3) to facilitate agreement upon common methods of measurement and the standardization of measuring instruments, and (4) to stimulate and to coordinate studies of the scientific aspects of telecommunications using electromagnetic waves, guided and unguided. The International Union itself is an organizational framework to aid in promoting these objectives. The actual technical work is largely done by the National Committee in the various countries. The new officers of the International Union are: President: Thomas B. A. Senior (U.S.A.) Past President: Pierre Bauer (France) Vice Presidents: Peter J.B. Clarricoats (UK) Hiroshi Matsumoto {Japan) Joseph Shapira (Israel) Maria A. Stuchly (Canada) Secretary-General: Paul Lagasse (Belgium) Assistant Secretary-General: Peter Van Daele Administrative Secretary: Inge Heleu The Secretary-General's office and the headquarters of the organi­ zation are located at Avenue Albert Lancaster, 32, B-1180 Brussels, Belgium. The Union is supported by contributions (dues) from 38 member countries. Additional funds for symposia and other scientific activities of the Union are provided by !CSU from contributions received for this purpose from UNESCO. The international Union, as of the XX!Vth General Assembly held in Kyoto, Japan, August 25-September 3, 1993, has ten bodies called Commissions for centralizing studies in the principal technical fields. Every three years the International Union holds a meeting called the General Assembly The next is the XXV!th, to be held in August, 1999, in Toronto, Canada. The Secretariat prepares and distributes the Proceedings of the General Assemblies. The International Union V arranges international symposia on specific subjects pertaining to the work of one or several Commissions and also cooperates with other Unions in international symposia on subjects of joint interest. Radio is unique among the fields of scientific work in having a specific adaptability to large-scale international research programs, since many of the phenomena that must be studied are worldwide in extent and yet are in a measure subject to control by experimenters. Exploration of space and the extension of scientific observations to the space environment are dependent on radio for their research. One branch, radio astronomy, involves cosmic phenomena. URS! thus has a distinct field of usefulness in furnishing a meeting ground for the numerous workers in the manifold aspects of radio research; its meetings and committee activities furnish valuable means of promoting research through exchange of ideas. Steering Committee: D. Cook P. L. Jensen D. Thorsen R. Frehlich J. McKie Technical Program Committee: S.K. Avery, Chairperson D. Backer R. Frehlich M. Kanda D. Thorsen G. Brown R. Gardner J. Lin E. Westwater L. Duncan U. !nan A. Mickelson D. Wilton vi Monday Morning, January 4, 1999 Session Al, 1015-Mon., ECCRIB40 IDENTIFICATION OF BURIED TARGETS Chairperson: Carl Baum (AFRL/DEHP) Al-1 BURIED ORDNANCE CLASSIFICATION USING POLARIZA- 1020 TIONS AND RESONANCES Chi-Chih Chen The ElectroScience Laboratory 1320 Kinnear Road Columbus, OH 43212 The scattered fields from a buried unexploded ordnance (UXO) contain linear polarization and late-time resonance features. In the past, the reso­ nance feature has been extracted from ground penetrating radar (GPR) to help classifying UXO's with reasonable success. The polarity feature, on the other hand, has not been fully utilized with GPR. It was found that the clut­ ter caused by the scattering from inhomogeneous media and surface roughness were major problems in both UXO detection and classification. Since this type of clutter has quit different polarization behavior from most UXO's, it is pos­ sible to further improve signal to clutter and signal to noise ratios by utilizing multiple polarization data. A new UXO classification approach proposed here is to collect both copolarization and cross-polarization data at various orientations by rotating the antenna sitting on top of a suspicious spot pre-selected from the field survey results. A good tool to locate suspicious spots has been found to be the magnetic sensor. Special processing technique is applied to extract the polarization and resonance features from this multiple-orientation data. Significant improvements in signal to clutter and signal to noise ratios were achieved. This also provides improved the radar sensitivity and the accuracy of the extracted resonances. A certain type of surface roughness, such as those caused by plowing or tire tracks, also creates linearly polarized scattered fields. But this type of scattering would not have resonant components. Therefore, the proposed new radar measurement and processing technique intends to utilize both linear polarity and resonance feature to achieve a better UXO classification technique. Al Mo-AM Al-2 MEASURES OF CROSS-POLARIZATION FOR 1040 SYMMETRICAL TARGETS Carl E. Baum Air Force Research Laboratory AFRL/DEHP Bldg 909 3550 Aberdeen Avenue SE Kirtland AFB NM 87117-5776 A radar signature of interest for certain symmetrical targets on or near (under) the earth surface is a null in the cross-polarization in the usual h, v measures of this cross-polarization in both narrowband and broadband/ transient contexts. These involve angles in the eigenvectors of the backscattering dyadic as well as norms of this dyadic and the cross­ polarization part. The measure of cross polarization in h, v coordinates is somewhat different for narrowband and broadband applications. In narrowband B applications one can diagonalize Ab to find appropriate angles, except in the case of rotational scatterers. In broadband applications such angles are not appropriate except in cases where they do not rotate with frequency/ time. The use of norms, such as 2-norm and root span, can be applied in both domains. The norms of the scattering dyadic which we have used are roll invariant. In the numerator of the norm-based measures we have a norm ~ of Ab- . There can be errors in our estimation of the lh direction. In h,v particular the local earth near the target of interest may not be perfectly horizontal. In such a case it may be preferable to define horizontal by the earth near the target. This corresponds to a rotation of the h, v coordinates. In such a rotation one may observe a reduction of the cross­ polarization. Of course, this applies for real rotation angles. If there is a complex angle ( riJ s ) in the scattering, then this comes from some other source (including a non-symmetrical target). There is also the problem of noise in the data. 2 Al Mo-AM Al-3 WIDEBAND SYNTHETIC APERTURE RADAR FOR 1100 DETECTION OF BURIED MINES AND UXO L. Carin, A. Sullivan and N. Geng Department of Electrical and Computer Engineering Duke University Box 90291 Durham, NC 27708-0291 Email: lcarin@ee. duke. edu M. Ressler and B. Merchant Anny Research Laboratory AMSRL-SE-RU 2800 Powder Mill Road Adelphi, Maryland 20783 The method of moments (MoM) is used to model three-dimensional scattering from unexploded ordnance (UXO) and mines buried arbitrarily in a layered soil environment. For the target depths of interest for buried UXO, the soil layering can become an important issue. The layered-medium Green's function is evaluated rigorously via the method of complex images, this allowing rigorous and efficient analysis of the ultra-wideband (UWB) problems of interest here. The results of the numerical modeling are compared with measurements taken with the Army Research Laboratory (ARL) synthetic aperture radar (SAR) system, which is implemented by placing four antennas atop a boom lift (the system is termed a "BoomSAR").
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