Transponder system.

摘要

Transponder system comprising RF transceiver means (1,2) arranged to transmit an interrogation signal and to receive backscattered reflections. A transponder (3) comprises means for receiving the interrogation signal and for converting it into a reflection signal which comprises higher harmonic frequencies e.g. by using an antenna circuitry including a dipole antenna interconnected via a circuit comprising a non-linear element like e.g. a diode and having a complex impedance, enabling the reflection of said higher harmonics. The RF transceiver means preferably are arranged to transmit a frequency or phase modulated signal. appropriate processing means are arranged for assessing the distance and direction of the transponder, e.g. by using at least two receivers (1,2) each of them being arranged to receive said reflection signal and connected to means for assessing the distance to the transponder. The transceiver means are connected to means (5) for computing, from the assessed distances between the receivers and the transponder, the location of the transponder.