Abstract: The variable polarization tracker is the key equipment for satcom-on-the-move antenna of satellite communi- cations. A broad-band high performance polarization agile tracker is designed using combined configuration of a step-shaped ridge and symmetrical turnstile junction of ortho mode transducer. In the polarization tracker, the functions of real-time track- ing, separation and extraction for the two H-V polarization RF signals can be realized. The proposed polarization tracker is simulated and optimized by electromagnetic simulation software HFSS and CST. The simulation results show that the proposed polarization tracker has good characteristics of polarization isolation and broadband. Over 2 GHz bandwidth in Ku-band, the polarization isolation between two H-V polarization channels is less than -34. 7 dB, the return loss is less than -22 dB.