This paper deals with the design of a new reconfigurable beam antenna used to improve the efficiency of spatial telemetry links on Nano-Satellite. This agile beam antenna is not built on the well-known array concept AESA (Agile Electronically Scanned Array) but using a new one called ARMA (Agile Matrix Radiating Antenna); MARPEM in French. In this paper there is the design of the circularly polarized matrix antenna, the generation of two beam forming modes, the design of the distribution circuit and the polarization circuits.