A small-angle approximation for bistatic polarimetry

Scattering matrices recorded with bistatic polarimetric radar systems can be described using bistatic Huynen parameters. These parameters not only depend on the properties of the target, but also on the bistatic angle. Quasi-monostatic radars as well as many bistatic radars exhibit configurations limited to small bistatic angles between receiver and transmitter. Therefore it is possible to apply a small-angle approximation to some of the Huynen parameters. In this paper the impact of this approximation on scattering matrices is investigated and the consequences of the approximation are discussed. From the discussion follows that for small bistatic angles the scattering matrix can be interpreted and handled like a monostatic scattering matrix apart from a perturbation along its antidiagonal. The findings are supported by simulation results.