Effects of magneto-ionic propagation on the polarization scattering matrix

Magneto-ionic propagation effects are considered at radio frequencies that are sufficiently high so that there is negligible physical separation between the ordinary and extraordinary propagation paths. It is recognized that the sensible magneto-ionic propagation effects are birefringence and Faraday rotation. A matrix representation for magneto-ionic propagation is employed in order to facilitate the determination of the effects of magneto-ionic propagation on the polarization scattering matrix of an arbitrary, monostatic radar target. It is shown that the propagation path must be calibrated with a known, four-way symmetric target when both birefringence and Faraday rotation are present, if it is desired to eliminate the effects of magneto-ionic propagation. However, the determinant of the polarization scattering matrix and the trace of the power scattering matrix are, in general, unaffected by magneto-ionic propagation. If birefringence is absent, then even if the radar target is arbitrary and unknown, the effects of Faraday rotation can be accounted for in a particularly simple manner if the scattering matrix is referred to circular polarization.