Rain rate estimation from attenuation measurements using a 35 GHz dual polarization microwave link

A 35 GHz dual polarization microwave link has been built at Penn State University. The operating principle of this instrument is essentially that of a pulsed bi-static radar. Rain attenuation measurements are made by placing a corner reflector in the beam of the antennas. Calibration and stability requirements are simplified compared to standard uni-directional propagation links. Taking the ratio of horizontal to vertical attenuation factors also reduces the sensitivity to instrument fluctuations, since receiver drifts which are slower than the polarization switching speed (2200 Hz) will be canceled out. This is a primary motivation for using the differential polarization technique. The results of differential sensitivity measurements by this instrument are presented.<>