Identification of the propagation depolarization matrix at 50 GHz using Italsat data

The Italsat propagation experiment at 50 GHz included a very sophisticated set of measurements aimed at identifying the full channel matrix in dual polarization. This was accomplished by measuring, in amplitude and phase, two linearly polarized signals fast commutated at the rate of 933 Hz. Co- and cross-polar measurements were taken at any semi-period of 0.5 ms, including the differential co-polar amplitudes and phases. The terms of the matrix (4 complex equivalent to 8 scalars) were reduced to 3 scalars making reference to particular parameters, called ”quasi physical” parameters (“anisotropy” and “canting angle”) that are very advantageous with respect to the original terms of the transfer matrix because of their physical significance, the relation with the meteorology, the mutual decorrelation and the relationship with attenuation (a parameter much easier to measure). The paper presents the statistical behaviour of Anisotropy and Canting angle and a model relating XPD in circular polarization (tightly related to anisotropy) to attenuation allowing to predict this parameter from attenuation measurements which are today widely available Worldwide.