Towards Substrate-Sensitive Chipless Tags for Sensing Applications

This paper studies wireless sensors made by printing chipless passive tags on dielectric sensitive substrates. A CPW- based resonator operating at 12.844 GHz and a wideband CPW- fed antenna operating in 9-14 GHz range were designed, realized and assembled to form a chipless tag. The RF identification frequency signature was integrated through a simple variation of the resonator geometry. The tag was printed on substrates of different dielectric constants to originally emulate an environmental variation. The results validate the tag sensor sensitivity. The resonant frequency shifted by 31 MHz while the dielectric constant varied from 3.55 to 2.20, thereby covering 0-58.6 %RH range with Kap- ton HN foils and 15-180°C range with Fluon ETFE foils.