The optimization and analysis of new waveguide polarizers have been carried out on the basis of rigorous full-wave model. These polarizers transform the dominant mode of input rectangular waveguide into an elliptically polarized wave of output square waveguide. The phase-shifting module is realized on the basis of one or two sections of a square waveguide having two diagonally placed square ridges. It has been found out that polarizers with single-section phase shifter can provide the bandwidth from 11 to 15% at the axial ratio level of r < 2 dB and the return loss level of R_L > 20 dB, whereas the two-section ones have the bandwidths more 23% at r < 1 dB and R_L > 23 dB.