Patent ID: 8816825

Claim:
A transponder for receiving a wireless electromagnetic interrogation signal and transmitting a wireless electromagnetic response signal, comprising: a first coil, coupled to receive the interrogation signal, the first coil acting as an antenna and generating a first wired electrical receive signal from the interrogation signal; at least one further coil, coupled to receive the interrogation signal, the at least one further coil acting as an antenna and generating a second wired electrical receive signal from the interrogation signal, wherein an axis of the first coil and an axis of each of the at least one further coil are aligned differently in the space; a plurality of full-wave rectifiers, coupled to the first coil and the at least one further coil, the plurality of full-wave rectifiers rectifying the first and second wired electrical receive signals; and a summing element, coupled to the plurality of full-wave rectifiers, the summing element summing up the rectified first and second wired electrical receive signals generated by the plurality of full-wave rectifiers and generating a pulsating sum signal, the frequency of the pulsating sum signal being corresponding to twice the frequency of the interrogation signal.