An RFID system for reading at least one RFID tag, the system comprising: an array of antennas, characterised in that each antenna (203, 205) is configured to emit a plurality of beams (213, 215) in different directions, wherein at least two beams of the plurality of beams (213, 215) of each pair of adjacent antennas (203, 205) are directed towards one another so that the at least two beams (213, 215) overlap, at least one RFID reader connected to at least two of the antennas (203, 205) such that at least one pair of adjacent antennas (203, 205) transmits simultaneously such that the overlapping beams (213, 215) interfere with one another to create an interference pattern, wherein the at least one RFID reader is configured to control at least one of the phase and the frequency of one of the interfering beams (213, 215) with respect to the other to move the interference pattern to read one or more RFID tags within the moving interference pattern; wherein two or more antennas (203, 205) of the array of antennas defines a dividing line, wherein the RFID system is configured to drive the antennas (203, 205) so that opposite sides of the dividing line are either i) alternately illuminated by the interfering beams or ii) illuminated by interfering beams of different frequencies, and wherein the RFID system is configured to determine movement of a tag across the dividing line from respectively either i) a difference in read rate of the tag during the times of alternate illumination or ii) a difference in read rate of the tag at the different frequencies, as the tag moves from one side of the dividing line to the other. an array of antennas, characterised in that each antenna (203, 205) is configured to emit a plurality of beams (213, 215) in different directions, wherein at least two beams of the plurality of beams (213, 215) of each pair of adjacent antennas (203, 205) are directed towards one another so that the at least two beams (213, 215) overlap, at least one RFID reader connected to at least two of the antennas (203, 205) such that at least one pair of adjacent antennas (203, 205) transmits simultaneously such that the overlapping beams (213, 215) interfere with one another to create an interference pattern, wherein the at least one RFID reader is configured to control at least one of the phase and the frequency of one of the interfering beams (213, 215) with respect to the other to move the interference pattern to read one or more RFID tags within the moving interference pattern; wherein two or more antennas (203, 205) of the array of antennas defines a dividing line, wherein the RFID system is configured to drive the antennas (203, 205) so that opposite sides of the dividing line are either i) alternately illuminated by the interfering beams or ii) illuminated by interfering beams of different frequencies, and wherein the RFID system is configured to determine movement of a tag across the dividing line from respectively either i) a difference in read rate of the tag during the times of alternate illumination or ii) a difference in read rate of the tag at the different frequencies, as the tag moves from one side of the dividing line to the other.