In this paper, the authors introduce a method for calibrating the end-to-end phase imbalance of polarimetric radiometers using a digital correlation technique. The method is based on the measurement of linearly polarized field at -45deg and +45deg angles with respect to the polarization plane of the transmitted field. This way, the effects of the polarization purity of the transmitted field and the polarization separation and cross-coupling of the antenna of the radiometer can be cancelled out. The remaining uncertainty consists of the pointing accuracy of the radiometer with respect to the transmitted field. It has been shown here that this effect can be reduced to the level that will make the method feasible