Precision and Accuracy in UHF-RFID Power Measurements for Passive Sensing

In spite of analog radio frequency identifica- tion (RFID) sensors are gaining increasing attention from acad- emic and industrial domains, their true applicability in the real world is still in question, since it is not clear whether and in which conditions the variation of the measured signals related to the sensing activity may be distinguished from the measurement uncertainties. The RFID platform for analog sensing, namely, with no dedicated sensing electronics, is here characterized in term of precision and accuracy with reference to the arrangement and the reproducibility of the setup. Numerical analysis and laboratory experimentations demonstrated that the precision of power metrics measurement is twice the resolution of low- cost readers and that the uncertainty on the distance and the alignment may play a major role on the data accuracy. The environment-independent indicator, such as the analog identifier, revealed once again to be a very stable and robust metric. In overall, the obtained results suggest that analog RFID devices can be used as indicative sensing platform to identify a few levels of the phenomenon under observation. The sensing granularity can be improved using low-power ICs, while classification algorithms could be applied to increase the robustness of the detection.