Importance

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Abstract

A battery-less transponder (12) for transmitting stored measurement data to an interrogation device (10) is described. The interrogation device (10) transmits an HF interrogation pulse for calling up the stored measurement data. The transponder (12) includes a resonant circuit (14) tuned to the frequency of the HF interrogation pulse, an energy storage element (C3) which is chargeable by rectification of the HF interrogation pulse and in the charged state furnishes the supply voltage for the transponder (12), and a voltage limiting means (Z, R) for limiting the voltage at the energy storage element (C3) to a predetermined voltage value. For detuning the resonance frequency thereof, a component (C4) of frequency-dependent impedance can be connected to the resonant circuit (14) via a switching element (T) which establishes the connection in dependence upon the starting of the limiting action by the voltage limiting means (Z, R).

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First Claim