LOW-GRAZING SCATTERING FROM BREAKING WATER-WAVES USING AN IMPEDANCE BOUNDARY MM GTD APPROACH/

Citation
Jc. West et al., LOW-GRAZING SCATTERING FROM BREAKING WATER-WAVES USING AN IMPEDANCE BOUNDARY MM GTD APPROACH/, IEEE transactions on antennas and propagation, 46(1), 1998, pp. 93-100
Citations number
22
Categorie Soggetti
Telecommunications,"Engineering, Eletrical & Electronic
ISSN journal
0018926X
Volume
46
Issue
1
Year of publication
1998
Pages
93 - 100
Database
ISI
SICI code
0018-926X(1998)46:1<93:LSFBWU>2.0.ZU;2-#
Abstract
The radar backscattering from water waves of various degrees of breaki ng is numerically examined, A hybrid moment method geometrical theory of diffraction (MM/GTD) technique previously used for small-grazing sc attering from perfectly conducting surfaces is reformulated using impe dance boundary conditions, allowing the treatment of large (but finite ) conductivity scattering media such as sea water. This hybrid MM/GTD approach avoids the artificial edge effects that limit the standard mo ment method when applied to rough surfaces, allowing the calculation o f the scattering at arbitrarily small grazing angles, Sample surfaces are obtained through the edge detection of video stills of breaking wa ves generated in a wave tank, The numerical calculations show that the strength of the backscatter is closely associated with the size of th e plume on the breaking wave, Strong interference appears in the both horizontal (HH) and vertical (VV) backscatter when the surfaces are tr eated as perfectly conducting, The VV interference is dramatically red uced when a sea water surface is used, but the HH interference is unaf fected. The interference leads to HH/VV ratios of up to 10 dB, The beh avior of the scattering is consistent with the multipath theory of sea -spike scattering.