A theoretical study of the dependence of the backscattering coefficients of a polarization lidar on the optical properties of a polydisperse medium has been performed. In the capacity of the latter a set of oriented circular plates with complex refractive index was considered. As a result, within the scope of this model we have succeeded in relating the ratios of the backscattering coefficients through simple analytic relations with the Euler angles defining the orientation of the plates and their complex refractive index.