Polarimetric optimisation based on the target covariance matrix

The covariance matrix optimisation method is considered in detail. It is shown that it provides a biased solution to the polarimetric optimisation problem. The method does not constrain the transmit/receive antenna vectors to be unitary and hence provides a polarisation dependent weighting to the Poincare sphere. A simple geometrical interpretation of the distortion in terms of the Deschamps parameters is provided.