Development and Application of Advanced Experimental Techniques for Ground Microwave Radiometry in All Weather Conditions

Sun-tracking microwave radiometry is an effective technique aimed at estimating the tropospheric attenuation in all-weather conditions by using the Sun emission as an equivalent beacon source. Though such technique definitely represents an interesting alternative to Earth-space electromagnetic propagation experiments, especially in the frequency region beyond 50 GHz for which space-borne beacons are hardly currently available, its application is not trivial, mainly because of the issues arising from the need to precisely pointing at the Sun: catching the Sun peak radiation might not be an easy task, especially if the frequency increases, i.e. the beamwidth gets narrower. This contribution focuses on the advanced experimental techniques developed in the framework of the ESA WRad project (funded by ESA) to maximize the accuracy of the W-band measurements collected by the multi-channel RPG MWR installed at Politecnico di Milano. Issues of the experimental campaign are highlighted and the associated solutions are discussed in detail.