Design of a UHF RFID fiber tag antenna with electric-thread using a sewing machine

An RFID tag antenna with electric-thread using a sewing machine is proposed. The characteristics of the electric-thread used as tag antenna are studied and the changes of conductivity for different sewing methods are analyzed. The electro-thread tag antenna is designed by the shape of alphabet characters. The radiation efficiency is about 33% and the measured maximum reading range is about 2.5m in an anechoic chamber. It is demonstrated that the electro-thread is possible to be directly applied to clothes as a brand or company marks. However, it is necessary to develop some additional technology for packaging to protect a tag chip from laundry and wrinkle.