Textile Chipless Tag based on Frequency Shift Coding Technique

In this paper a fully-textile RFID chipless tag based on the frequency shift coding technique is presented. The proposed tag consists of a 50 Ω microstrip line loaded by a hairpin resonator. To achieve a compact size, the resonator is slotted on the ground plane of the microstrip line. By using a single hairpin resonator, a 3-bit tag is obtained. In particular, by selectively cutting the fingers of the hairpin resonator, a frequency shift of its resonance is achieved. In order to facilitate the integration of the proposed device in clothes, textile materials have been used for both the substrate and the conductive parts. Numerical and experimental data demonstrate that the proposed device can be exploited as a simple tag or as a touch sensor.