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Microwave Scattering Model for Grass Blade StructuresIn this paper, the electromagnetic scattering solution for a grass blade with complex cross-section geometry is considered. It is assumed that the blade cross section is electrically small, but its length is large compared to the incident wavelength. In a recent study it has been shown that the scattering solution for such problems, in the form of a polarizability tensor, can be obtained using the low-frequency approximation in conjunction with the method of moments. In addition, the study shows that the relationship between the polarizability tensor of a dielectric cylinder and its dielectric constant can be approximated by a simple algebraic expression. The results of this study are used to show that this algebraic approximation is valid also for cylinders with cross sections the shape of grass blades, providing that proper values am selected for each of three constants appearing in the expression. These constants are dependent on cylinder shape, and if the relationship between the constants and the three parameters describing a grass blade shape can be determined, an algebraic approximation relating polarizability tensor to blade shape, as well as dielectric constant, can be formed. Since the elements of the polarizability tensor are dependent on only these parameters, this algebraic approximation can replace the cumbersome method of moments model. A conjugate gradient method is then implemented to correctly determine the three constants of the algebraic approximation for each blade shape. A third-order polynomial fit to the data is then determined for each constant, thus providing a complete analytic replacement to the numerical (moment method) scattering model. Comparisons of this approximation to the numerical model show an average error of less than 3%.
Document ID
19970014810
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Stiles, James M.
(Michigan Univ. Ann Arbor, MI United States)
Sarabandi, Kamal
(Michigan Univ. Ann Arbor, MI United States)
Ulaby, Fawwaz T.
(Michigan Univ. Ann Arbor, MI United States)
Date Acquired
August 17, 2013
Publication Date
September 1, 1993
Publication Information
Publication: IEEE Transactions on Geoscience and Remote Sensing
Publisher: Institute of Electrical and Electronics Engineers
Volume: 31
Issue: 5
ISSN: 0196-2892
Subject Category
Communications And Radar
Report/Patent Number
NAS 1.26:204091
NASA-CR-204091
Accession Number
97N71246
Funding Number(s)
CONTRACT_GRANT: NAGw-1101
CONTRACT_GRANT: JPL-958438
Distribution Limits
Public
Copyright
Public Use Permitted.
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