Optimal Polarization in Bistatic Scattering

Abstract

The theory of optimal polarization in backscatter by Kennaugh and Graves is extended to the bistatic case to establish that there exist, in general, a set of polarizations characteristic of the features of the scatterer in each scattering geometry, namely optimal polarizations, that could be used as in backscatter to enhance radar detection of man-made scatterers. It will be shown that the optimal polarizations of each antenna used for transmitting in the bistatic scattering geometry and for receiving in the reciprocal scattering geometry are the same, so that both antennas must be tuned to the optimal polarizations for the scatterer. These optimal polarizations can be found by two alternative methods in a two-dimensional complex vector space: (a) as the eigenvectors of a certain pair of positive-definite power scattering matrix and reciprocal power scattering matrix; or (b) as the solutions of a pair of nonlinear equations relating the two sets of eigensolutions in (a). It will also be shown that both methods can be formally cast in a certain four-dimensional complex vector space in the forms that resemble the equations of Graves and Kennaugh in backscatter in a two-dimensional complex vector space.