• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.1
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• pp.75-82
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• 2009

In this paper, we proposed a U-shaped broadband RFID tag antenna with a parasitic element operating at UHF band. The proposed tag antenna consists of a U-shaped half wavelength dipole antenna and an inverse U-shaped parasitic element inside the U-shaped dipole antenna. In order to have good impedance matching, the commercial tag chip is attached to the lower center of the rectangular shaped feed. On the condition of VSWR<2, the tag antenna had the measured bandwidth of 4.96 % from 882 to 927 MHz and showed the gain deviation of less than 3.16 dB. On the condition of VSWR<5.8, the tag antenna satisfies the worldwide UHF RFID bandwidth and is showed the gain deviation of less than 5.07 dB. The minimum gain deviation characteristic appears near the center of bandwidth which minimizes variation of gain deviation characteristic with respect to the frequency.