For the problem of radar function simplification and variety of the radar, it need to change most hardware for upgrading radar function at present (in particular antenna system), open system architecture by antenna reconfigured to achieve software defined radar is proposed. The transmission signal of the architecture is arbitrarily generated via software based on array unit and the antenna can be arbitrarily cut out via software coding according to system function and be reconfigured. The RF end of antenna unit is directly connected to bi-phase code modulator, by orthogonal bi-phase code modulating the single channel arbitrary digital beam forming can be broken through and the channel consistence problem can be resolved, so the antenna configuration can be more flexible. The architecture can be used not only in conventional phased array radar, but also in MIMO, cognitive radar and radar and communication integration. The field test has been accomplished for multichannel multiplex digital beam radar system platform based on software defined development; it has been proved that the architecture of the radar system is feasible.