Transponders, interrogators, systems and methods for elimination of

Abstract

A Radio Frequency Identification (RFID) system having an interrogator (12) and a transponder (14). The interrogator has a first tuned circuit (28) of a powering frequency for sending a powering burst to a transponder (14), a filter/demodulator (64) for receiving an wireless, modulated RF response from a transponder (14). The interrogator (12) further has a second tuned circuit (29) in electrical communication with a modulator (48), the second tuned circuit (29) having a selected bandwidth about a communication frequency, the selected bandwidth not substantially overlapping the powering frequency and encompassing the bandwidth of the modulated carrier of the RF response. The interrogator also has a controller (16) in electrical communication with the filter/demodulator (64) and the tuned circuits (28,29) and capable of enabling the first tuned circuit (28) to send the powering burst during a first time period and of enabling the modulator (48) in electrical communication with the second tuned circuit (29) to receive the RF response during a second time period. The transponder has a tuned circuit (34), a tuning circuit (54,56) in electrical communication with the tuned circuit (34) for modifying the frequency characteristics of the tuned circuit (34) such that it is can be tuned during the powering burst to the powering frequency and to be tuned during the RF response to the communication frequency. The transponder (14) also includes a demodulator (66) in electrical communication with the tuned circuit (34) for receiving the RF interrogation therefrom and for demodulating data from the RF interrogation.