Dissertation
Numerical studies of the SSA and SSA+ for scattering from randomly-rough surfaces
Washington State University
Doctor of Philosophy (PhD), Washington State University
05/2010
DOI:
https://doi.org/10.7273/000006088
Abstract
In recent years, researchers have been working to develop a "practical" rough surface scattering model which provides sufficiently accurate results at a reasonable computational cost. Previously it was shown for the 1-D Dirichlet problem that the SSA+, which was developed from the NLSSA and includes some multiple scattering, is a good candidate for a practical model because it satisfies all three of our criteria [Broschat and Wang, Waves in Random and Complex Media, Aug. 2009]. The SSA+ is only useful when the lowest-order SSA itself gives reasonable results. Thus we first present a systematic study of the accuracy of the lowest-order SSA for 1-D surfaces and a Pierson-Moskowitz roughness spectrum. Incident angles of 10, 45, 70, and 85 degrees and wind speeds of 3, 4, 5, 7, 10, 15, and 20 m/s are considered. It is found that for very small kh (<0.06), where k is the incident wavenumber and h is the rms surface height, the accuracy of the SSA is limited. In general, the smaller the incident angle, the greater the range of scattering angles over which the SSA is accurate. As the values of kh become large, the SSA starts breaking down. We extend the SSA+ to dielectric surfaces. As with the Dirichlet problem, the SSA+ bistatic scattering cross section can be written as the sum of the lowest-order SSA and a pair of correction terms which are associated with non-local scattering. The SSA+ is derived from the NLSSA by applying two additional approximations which reduces a 5-D integral to a 2-D integral. Numerical results for the lowest-order SSA and the SSA+ are presented for a Gaussian roughness spectrum and an angle of incidence of 80 degrees. Monte Carlo SSA+ results are compared with those obtained using a Monte Carlo integral equation technique to obviate the issues of taping and angular resolutions. Finally we include the derivation of the SSA+ expression for 2-D dielectric surfaces. As with the 1-D problem, the SSA+ bistatic scattering cross section can be written as the sum of the lowest-order SSA and a pair of correction terms which involve 4-D integration
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Details
- Title
- Numerical studies of the SSA and SSA+ for scattering from randomly-rough surfaces
- Creators
- Yanqiu Wang
- Contributors
- Shira Lynn Broschat (Chair)John Brand Schneider (Committee Member) - Washington State University, School of Electrical Engineering and Computer ScienceScott Hudson (Committee Member) - Washington State University, School of Engineering and Applied Sciences (TRIC)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Electrical Engineering and Computer Science
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 78
- Identifiers
- 99901055128001842
- Language
- English
- Resource Type
- Dissertation