Beam-switchable phased array antennas for the near-field RFID applications

This paper presents a new RFID reader antenna design with its radiation beam switchable to track the tags in in the near-zone of array aperture. The antenna is realized by using microstrip antenna array with a beam-forming network based on Butler matrix. The radiation of array is focused in the near zone to avoid interferences resulted from the scatterers in the vicinity of antenna. The design approach, numerical simulation and experimental measurement over an antenna prototype are presented to validate the feasibility.