In the study of meteorological phenomena by radar, it has been shown that dual-polarization radar measurements can yield useful data about precipitation structures within the radar beam. The techniques available for dual-polarized radar measurement are differential reflectivity (ZDR), linear depolarization ratio (LDR), and circular depolarization ratio (CDR). This paper presents a theoretical analysis of backscattering from a volume filled with raindrops using Rayleigh scattering theory. A generalized radar equation is given in matrix form, and the dependence of backscatter measurements in terms of a rainstorm model including raindrop shape, size, and canting angle is examined. Calculated results which show the dependence of ZDR on beam elevation angle and polarization angle are presented. Some results for LDR and CDR are presented, showing how these quantities depend on raindrop parameters.