Calibration techniques and devices for correlation radiometers used in polarization measurements

The polarized sky emission can be detected by measuring its Stokes parameters through correlation radiometers. In order to compensate for the variation of the characteristics of the various components of the radiometers and of the environmental parameters, an on line calibration is required. In fact, the evaluation of the proportional factor between the detected signal and the level of the radiation is not sufficient for a complete characterization of the radiometers, since, in polarization measurements, the detection occurs in a two-dimensional space, that is the Q and U Stokes parameters. In this case special procedures and devices are needed.