SIW textile antennas as a novel technology for UWB RFID tags

A wearable ultra-wideband (UWB) textile antenna based on substrate integrated waveguide technology is presented for application in the next generation radio-frequency identification (RFID) systems operating in the low-duty cycle restricted [3.4-4.8] GHz UWB band. The design of a UWB antenna for application in smart textiles is very challenging. For end users, the antenna should be unobtrusively integrated into smart textile and comfortable to wear. From a system point of view, good impedance matching and radiation characteristics over a very large bandwidth are of major importance, even under harsh operating conditions. Our approach consists of applying copper tube eyelets to implement a cavity-backed slot antenna in textile materials. A prototype was realized and measured. The measured return loss characteristic and radiation performance after bending and deploying the antenna on different human body parts prove that our antenna is extremely suited for on-body use. A -10 dB-bandwidth of 1.33 GHz, or 33 %, was realized, in which the radiation pattern remains quasi invariable.