Identification system using hertzian waves, consisting of an interrogation station and a responder unit

摘要

PCT No. PCT/FR90/00139 Sec. 371 Date Oct. 28, 1991 Sec. 102(e) Date Oct. 28, 1991 PCT Filed Feb. 27, 1990 PCT Pub. No. WO90/10200 PCT Pub. Date Sep. 7, 1990.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. This allows a differentiation between the emission inquiry signal and the response signal, since the inquiry signal wave is received by a circular polarization-type antenna of the responder unit according to a first rotation direction of the polarization. The responder unit is adapted to re-emit a modulated response signal constituted by a radio wave of the same kind as the inquiry wave of circular polarization-type according to a second rotation direction of the polarization in the opposite direction to the first rotation direction.