Apparatus and method for simultaneously reading out of passive inductive transponders

摘要

The present invention relates to a transponder reading device for reading out a plurality of inductive passive transponders having a resonant circuit. A transmitter is provided to create an alternating magnetic field having an operating frequency fB, in which the number of transponders may be placed such that same are magnetically coupled to each other. A retuning means is further provided which is arranged in the alternating magnetic field and has such a frequency-dependent impedance that a voltage induced in the resonant circuits of the transponders by the alternating magnetic field has a maximum in the range of the operating frequency fB.