No abstract

Passive UHF RFID system have drawn considerable attention because it can provide a long reading range, high data rate, and small antenna size. However, a passive UHF RFID system has challenges in tagging a metallic object due to effects of conducting materials on the tag antenna performance. This study presents investigation and analysis of effects of a metallic surface on the performance of commonly used label-type dipole tag antenna. The performance is evaluated based on the return loss and change in resonance frequency of the tag antenna. To conduct the performance analysis, a folded dipole and a meandered dipole antenna are proposed for a passive tag. The proposed antennas are designed on low profile antenna which can operate at 866 MHz in the UK and Europe UHF RFID frequency band. The design also takes into account of impedance matching, feeding techniques, size-reduction, and bandwidth of the passive UHF tag antenna. Finally, simulation result shows that when the tag antenna is mounted closer to a metallic surface, the return loss of tag antenna is significantly increased and the resonance frequency is also shifted from the desired frequency.Index Terms-Effect of metal, folded dipole antenna, meandered dipole antenna, tag antenna performance.

Passive radio frequency identification (RFID) system operating in the ultrahigh frequency (UHF) band ranging from 860 MHz to 960 MHz is getting considerable attention in the recent years as it provides a long reading range, high data rate, and small antenna size. However, the passive UHF RFID tag does not work when it is directly mounted on metal objects. The performance of the passive UHF RFID tag is becoming increasing important for tagging metallic objects, in particular, in the warehouse applications. In this paper, a micro-strip patch antenna is proposed for the passive UHF RFID systems to tag metallic objects. The proposed design of the micro-strip patch antenna is supplemented by simulation and reading range measurement results. The prototype antenna measurements show a maximum reading range of 4.5 m and a reliable reading range of 1.89 m on metallic objects. The experimental results show that the prototype micro-strip patch antenna works very well on the metallic objects.