This thesis discusses the development of an S-band radar used to measure differential reflectivity in multiple polarization planes. The radar uses a novel polarization switch which allows reflectivity measurements in any linear polarization. A dedicated microcomputer and a digital hardware system collect the reflectivity data in any of four pairs of orthogonal polarization planes, i.e. data to calculate four ZDR values. This design permits the operator to change many of the important radar parameters, including the number of range gates averaged. Spatial averaging may be also selected. A unique feature of this data collection system is a digitial linearizer which converts the data from the logarithmic IF amplifier into linear power levels prior to integration. / M.S.