RFID Reader Antennas for Tag Detection in Self-Confined Volumes at UHF
Carla R. Medeiros, Jorge R. Costa, Carlos A. Fernandes
IEEE Antennas and Propagation Magazine
Volume: 53, Issue: 2, April 2011
RFID, UHF antennas, microstrip antennas, RFID antennas, near-field UHF RFID, smart RFID reading surfaces
Confinement of the detection region is a critical issue for some important RFID applications, where the coarse location of the object is required along with its identification. In the UHF band, it is a challenge to confine antenna radiation to reasonably sharp interrogation volumes, < lOA? , without resorting to physical barriers. This paper presents a novel approach for RFID reader radiating structures that self-confine tag detection to a desired volume, avoiding undesired readings outside the interrogation volume. The proposed solution simultaneously covers the three world-assigned RFID frequency subbands at UHF. To demonstrate the effectiveness of the solution, the proposed configuration was integrated into bookshelves, a conveyor belt system, and a proximity point reader. Together with an appropriate control application, these form the building blocks of a smart store with automatic inventoryLn9 and billing capability. The radiating structure concept was explored by fullwave simulations, and it was validated with both near-field measurements and with tag-reading scores. Short demonstration
videos are available online.
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