Large Bandwidth Ground Scattering Model (Bredbandig Spridningsmodell foer Mark)

摘要

A model is set up for diffraction limited radar backscatter from natural terrain. In contrast to what is the case in conventional terrain scattering models, the radar is thus assumed capable of achieving a linear resolution on the ground of wavelength order. The situation may be realized, for instance, by a SAR configuration adopting a large synthetic aperture length and a low frequency radar band of large relative bandwidth (e.g. 10-100 MHz). The radar signal will be represented by complex numbers, while the scattering amplitude is split up into a complex linear and a complex skew-linear part. Polarization effects may in this way be completely accounted for, by a minimum of notation. The freedom from notational redundancy is important, in particular, in a subsequent treatment of inverse scattering, retrieving the ground topography on the basis of diffraction limited SAR data. It is demonstrated that for scalar Kirchoff theory to be even approximately correct, the ground must undulate only gently with respect to the chosen state of linear polarization.