Patent ID: 8907767

Claim:
A radio frequency identification (RFID) reader, comprising: a transmission unit for transmitting a plurality of interrogation signals; a reception unit for receiving return signals produced from an RFID tag responding to the plurality of interrogation signals, wherein the return signals comprise both return signals traveling along direct paths from the RFID tag and return signals traveling along reflective paths from the RFID tag; and a control and processing unit for controlling the transmission unit to transmit the plurality of interrogation signals and processing the return signals received from the RFID tag to identify the RFID tag and compute the distance between the RFID reader and the RFID tag, the control and processing unit being operative to direct the transmission unit to transmit the plurality of interrogation signals such that they exhibit varying antenna polarizations, the antenna polarizations being chosen such that the return signals produced from the RFID tag responding to the plurality of interrogation signals and traveling along the reflective paths from the RFID tag to the RFID reader will sum to approximately zero, wherein each return signal received from the RFID tag includes tag information comprising an identifier for the RFID tag, and wherein the control and processing unit discards a preconfigured top percentage and a preconfigured bottom percentage of the return signals from a mean of the return signals when computing the distance between the RFID reader and the RFID tag.