Abstract: A radar system for primary and secondary airspace surveillance, and especially for the detection and tracking of moving targets, consisting of a number of elementary satellites connected to nonrigid structures and of a main satellite, which performs accurate measurement of the position and altitude of elementary satellites and real-time adaptive combination of radar signals coming from them, so as to provide a large-phased array operating in the microwave band. This system overcomes the limitations on dimensioned large space-bound antennae found in the literature, minimizing the incidence and effects of undesired echoes and interference and assuring high detection accuracy. The fact that the elementary satellites are all the same (modular) makes possible gradual assembly of the system with possible expansion in time and assures particularly high operating availability.