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RFID Reader Antennas For Tag Detection in Self-Confined Volumes at UHF

Medeiros, C. R. ; Costa, J.R. ; Fernandes, C. A.

IEEE Antennas and Propagation Magazine Vol. 53, Nº 2, pp. 39 - 50, April, 2011.

ISSN (print): 1045-9243
ISSN (online): 1045-9243

Journal Impact Factor: 1,312 (in 2008)

Digital Object Identifier: 10.1109/MAP.2011.5949323

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Abstract
Confinement of the detection region is a critical issue for some important RFID applications where object coarse location is required along with its identification. It is a challenge at the UHF band to confine antenna radiation to reasonably sharp interrogation volumes <10Ć3 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 covers simultaneously the three world assigned RFID frequency sub-bands at UHF. To demonstrate the effectiveness of the solution, the proposed configuration is integrated into bookshelves, a conveyor belt system, and a proximity point reader which form, together with appropriate control application, the building blocks of a smart store with automatic inventorying and billing capability. The radiating structure concept is explored by full-wave simulations and it is validated both with near-field measurements and with tag reading scores. Short demonstration videos are available on-line.