A small RFID tag antenna with bandwidth-enhanced characteristics and a simple feeding structure

A small RFID tag antenna in a UHF band is proposed in this article. Using dual resonance, the antenna has bandwidth-enhanced characteristics without an additional matching circuit. The meander shape of the proposed antenna helps to reduce the antenna size. The bandwidth of the antenna is enhanced by two radiators that create dual resonance in adjacent frequencies. When the length and location of each radiator are adjusted, the antenna can make dual resonance at an arbitrary impedance point, thereby enabling the antenna to match an RFID tag chip in a wide frequency range. According to the simulated and measured results, the proposed antenna has almost double the bandwidth of a regular antenna. (C) 2008 Wiley Periodicals, Inc.