Compact size UHF RFID tag for racing pigeon ring applications

An RFID (Radio Frequency Identification) tag antenna for racing pigeon ring applications is proposed. The structure of this UHF tag is a loop type with compact planar size of 30 × 8 mm2, and because it is printed on a thin polyimide film of thickness 0.063 mm, it can therefore be wrapped into a double layer plastic cylindrical ring of size similar to those used for racing pigeon. To achieve good impedance matching, a series chip resistor is loaded into the tag antenna, so that it can conjugate match with the tag chip input impedance. The measured 10-dB return loss of the tag antenna was 902–929 MHz, and it has a maximum reading range of 20 cm when inserted into a real preserved dried pigeon feet specimen.