UHF Omnidirectional Bent Dipole Antenna for Item-level RFID Applications

摘要

Radio frequency identification (RFID) technology provides wireless identification and tracking capability that is more convenient than the use of bar codes and optical scanners [1]. In contrast to the RFID applications for pallet and case tracking, RFID applications at an item-level is driven by the tagging of fairly small and high volume items - retail apparel, jewelry, rented apparel/laundry, aircraft parts, drugs and postal packages, books, documents - at the request of retailers, military forces, postal authorities, libraries, museums, art galleries, hospitals, and so on. Item-level tagging offers far more benefits than pallet and case tagging. They include safety and security, error prevention and brand enhancement as well as cost, service. Antenna is one of the key factors for RFID systems. The detection range and accuracy are directly dependent on the performance of reader/tag antennas. In addition, optimized antenna design will benefit the RFID system with longer range, better accuracy, reduced antenna fabrication cost, and simple system configuration and implementation. The challenges of antenna design for item-level RFID applications include controlling reading zone of the reader antenna, designing platform tolerant tag antenna as the tags are always attached to specific objects which may be lossy material or metal; maintaining tag performance with serious multi-coupling between the tag antennas as the tags are placed in very close proximity, and so on. In this paper, we present the design of an UHF RFID tag antenna with omnidirectional reading pattern. The RFID tag using such antenna exhibits very good omnidirectional reading pattern, which shows great potential for item-level RFID applications in restaurants or libraries to track items such as plates, books, and so on.