The aim of this paper is to present an integrated beam-scanning antenna for a submillimeter wave instrument. The ultimate goal is to be able to scan the limb of the Martian surface to measure the wind, temperature and water vapor. The scanning of the limb can be achieved by the mechanical translation of a micro-lens using a piezo-electric motor integrated with the receiver. A prototype has been fabricated and measured at 550 GHz, achieving a scanning loss lower than 0.4 dB for beam angles up to 15 degrees.