Very small size UHF RFID tag for racing pigeon ring applications

A very small size RFID (Radio Frequency Identification) tag antenna specifically designed for racing pigeon ring applications is proposed. The structure of this UHF tag is a closed-loop type printed on a 30 × 8 mm 2 polyimide film of thickness 0.063 mm. Thus, it can be wrapped into a double layer plastic cylindrical ring of size similar to those used for racing pigeon. By simply tuning the inner width of the loop, good conjugate matching between the tag chip input impedance and the tag antenna can be achieved. When inserted into a real preserved dried pigeon feet specimen, the measured 10-dB return loss of the tag antenna was 901-929 MHz, and it has a maximum reading range of 22 cm.