Subsystem of Phased Array Antennas With Adaptive Beam Steering in the Near-Field RFID Applications

An antenna subsystem is presented for RFID reader applications at 2.45 GHz in the near-zone tag detection. The subsystem is programmable to adaptively steer the radiation beam from one spot to another inside the target zone, and allows the RFID to achieve a better signal reception by changing the beam patterns along the horizontal cut. The created beams have narrow spots, and may potentially reduce the interference by the electromagnetic scattering from the nearby metal structures. An antenna prototype is examined to validate the feasibility.