Various wearable embroidery RFID tag antenna using electro-thread

Various embroidery tag antennas shaped like Korean alphabet shape and YJ kindergarten logo shape UHF RFID tag antennas have been designed with 70 D, 100 D and 200 D of electro-thread. The two structures have T-matching structures. The conductivities of three different electro-threads are measured. The measured and calculated resistance values of electronic-threads are used for the simulation. The Korean alphabet UHF RFID tag antenna has 1.5 m reading range. The second design, YJ kindergarten logo shape has been designed with 100 D electro-thread and with two different sewing directions. The reading range with the second tag with horizontal sewing direction achieves 30 cm which is 10 cm longer than that of vertical sewing method. The simulation of embroidery tag antenna with electro-thread requires the resistance value of embroidery itself instead of resistance value of the electro-thread. The different shape of embroidery tag antenna will be designed and the bonding method between electro-thread and RFID chip or strap should be studied.