Abstract: A broadband low profile antenna of “Satcom on the Move”is presented. The antenna aperture is designed as array structure, with an aspect ratio of 4:1. The cell element can be comprised of double primary horn antennas with metal grids, the Orthomode Transducer(OMT) and H-T waveguide power divider. Through the reasonable using of space distribution, two feed networks are provided to connect with the cell element separately, which are composed of E-field and H-field waveguide power dividers. The simulated results demonstrate that for an optimum design, the bandwidth of the antenna can be up to 30%. What is more, the antenna has a good performance to process two independent polarizations simultaneously, while the aperture and profile could be minimized.