Excellent efficiency of a linearly polarized microstrip array in Ku-band is achieved by having proper impedance matching throughout the array and by properly using the corporate and series fed by microstrip transmission lines. The cavity-backed microstrip patch is used to obtain relatively wide bandwidth. The auto-tracking Ku-band antenna in the azimuth direction has developed with a very low profile for vehicle\u27s rooftop mounting, as well as, a low manufacturing cost. The main beam of array is tilted 15° away from the broadside direction to provide optimum coverage for Korea satellite III