Abstract: Identification system constituted by an interrogation station or interrogator 1 itself formed by a radio frequency wave transceiver and preferably on an ultra frequency wave length 5, and, on the other hand, by a responder unit 2 adapted to receive the wave and to re-emit (echo) it following the given coded modulation to the responder unit. The interrogator is adapted to receive this echoing wave 11 and to demodulate it in order to derive the identification code therefrom. The interrogator has an emission antenna adapted to emit an inquiry signal constituted by a radio wave emitted in plane polarization. The responder unit has two adjacent antennas, respectively, for the reception of the inquiry wave and for its re-emission (echo) after modulation. The two antennas are of the circular polarization type and each functioning in a direction of rotation of the polarization opposite with respect to each other.