A resistant textile tag antenna for RFID UHF frequency band

Wearable textile systems are nowadays a fast growing field. Besides lower prices, wearable tags antenna have to resist laundry cycles which means high pressure, high temperature and humidity. This paper introduces a novel RFID textile tag antenna, made of two distinct antennas coupled together to protect UHF RFID system from environment stress : a circular small-loop antenna packaged with the RFID chip and a wideband log-periodic antenna made of electro-thread. Electric proprieties of the chip, the small-loop antenna and matching between both are shown. Used method to characterize electro-thread and the choice of electro-thread are presented. Finally the whole tag antenna is simulated and results are presented in part IV. In the UHF band we found the matched reflection coefficient less then -10 dB and the antenna´s half power beamdwith has 80°. According to Friis equation we can estimated the read range at 4 meters in the RFID UHF band.