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H. Arthaber:
"Verfahren und System zur Ortung von Objekten";
Patent: EU, No. Ep2739989 A1; submitted: 07-31-2012.

The invention relates to a method for locating an RFID tag using at least one RFID reading device. The invention is characterized in that the RFID reading device transmits a query signal which comprises a broadband signal; the RFID tag modulates the query signal with a code signal by varying the antenna impedance of the RFID tag and reflects said signal as a reflected signal; the RFID reading device receives the reflected signal and obtains the code signal and a scattered broadband signal from the reflected signal; the RFID reading device determines a travel time of the broadband signal by comparing the broadband signal with the scattered broadband signal; the RFID reading device determines the distance between the RFID reading device and the RFID tag from the travel time difference.