DTIC ADA385827: Advanced Propagation Modeling for Military pdf

DTIC ADA385827: Advanced Propagation Modeling for Military

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This research summarizes research on scattering from a wedge-on-a-plane geometry as a means to better understand the effects of such a perturbation on the propagation of electromagnetic waves over such a surface. The method of solution is the method of ordered multiple interactions (MOMI) and it was found that only two iterations were required to obtain sufficient accuracy for scattering into the entire upper half-space. Significant results from the study were as follows. When the tip of wedge has a radius of curvature less than about one em wavelength, the wedge tip may be considered to be perfectly sharp. The sharp tip causes an induced current that extends well beyond the support of the incident field for TM polarization particularly. The effect of this on the scattered field is most pronounced in the low grazing angle backscatter direction. The dominant scattering mechanism in the low grazing angle backscattering direction is interference between the tip diffracted field and the tip diffracted-planar reflected field.

In this intereference region, the ratio of TE to TM scattered powers can approach 0 dB because peaks of the TE cattering correspond to the minima of the TM scattering pattern. This intereference pattern appeared to persist when random roughness was added to the surface. The forward scattering is dominated by the flat surface specularly field, the field that is specularly reflected from the sloping surface of wedge nearest to the source, and tip diffraction into the forward direction. The resulting intereference in the forward direction gives rise to ‘shoulders’ in the specularly reflected field pattern

• Creator/s: Defense Technical Information Center
• Date: 11/16/2000
• Year: 2000
• Book Topics/Themes: DTIC Archive, Browe, Bryan E, VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ELECTRICAL AND COMPUTER ENGINEERING, *ELECTROMAGNETIC SCATTERING, SOLUTIONS(GENERAL), FORWARD SCATTERING, WEDGES, INDUCED ENVIRONMENTS, POLARIZATION, METHOD OF MOMENTS

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