In the dense distribution environment, the Ultra-High Frequency Radio-Frequency IDentification (UHF RFID) tags are interfered by the mutual impedance of adjacent tags, which can lead to a decline in reading rate. Based on the two-port network and Yagi-Uda antenna array theory, this paper firstly analyzes the relationship of antenna structure and mutual impedance. Then, the reasons for the change of the tag antenna transmission coefficient and the gain are explained. At last, a design of stacked tags for mutual impedance in intensive distribution environment is proposed. The numerical simulation and measurement results show that the new kind of RFID tag, not only has better performance in stand-alone scenario, but also has less interference between each other. It is suitable for RFID system in dense environment of multiple tags.
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2015, Vol. 37 
