Patent ID: 8768248

Claim:
A method for deriving information from an RFID tag, comprising: transmitting RFID tag interrogation signals from an array of antenna elements to an RFID tag; processing signals received by each of the antenna elements in the array of antenna elements from the RFID tag to alter relative phase between them, where processing received signals comprises: selecting received signals from one of the antenna elements in the array of antenna elements as a reference signal; adjusting the relative phase of the received signals from each of the other antenna elements in the array of antenna elements relative to the reference signal; and combining the adjusted relative phase received signals with the reference signal to form an amplitude weighted combination of phase aligned signals having a higher gain than the signals received from the RFID tag from any one of the antenna elements, where combining the adjusted relative phase received signals with the reference signal comprises: autocorrelating the reference signal; correlating each of the received signals from the other antenna elements in the array of antenna elements with the reference signal; separately accumulating the correlation results; delaying the signals received from each of the antenna elements in the array of antenna elements to compensate for accumulation delay; and applying the accumulated correlations from each of the antenna elements in the array of antenna elements as a beam forming coefficient to the delayed signals received by that antenna element to produce beam steered signals from each of the said antenna elements; and deriving information from the RFID tag from a combination of the processed received signals.