Patent ID: 8690071

Claim:
A transponder comprising an antenna for receiving a reader generated electromagnetic field, transferring energy from the reader to the transponder, the electromagnetic field alternating with a carrier frequency, a rectifier having an antenna side linked to the antenna for receiving an alternating current from the antenna and a transponder side for supplying the transponder with a direct current, and a data signal source for generating an electronic data signal encoding digital information, wherein the data signal source is coupled to the transponder side of the rectifier, the rectifier modulating the electromagnetic field with the data signal so that the data signal is transmitted to the reader, wherein the transponder further comprises a subcarrier modulator for modulating a subcarrier wave with the data signal to obtain a transmit signal, and wherein the subcarrier modulator is coupled to the transponder side of the rectifier, the rectifier modulating the electromagnetic field with the transmit signal so that the transmit signal is transmitted to the reader.