Miniaturized Chipless Sensor With Magnetically Coupled Transducer for Improved RCS

Chipless sensors have opened an intensive area of research due to its inherent ultralow fabrication cost, although much improvement remains to be done before this technology succeeds as a widespread wireless monitoring solution. For example, addressing miniaturization and sensitivity in uniplanar designs generally implies a tradeoff between radiation performance and sensitivity due to the restrictions imposed by the transducer. Instead of an electrically connected capacitor acting as the transducer, this letter proposes a magnetically coupled resonator, which permits maximizing the radar cross section for a determined available area. The idea was validated through the measurements of a humidity sensor resulting in a resonance frequency variation of 104.4 MHz around 2.4 GHz in a range of 8.2-90.5 %RH.