Development and metrological evaluation of a microstrip resonator for gas sensing applications

This paper is about the design and the realization of a one-port microwave microstrip resonator working in the frequency range from 3 GHz to 6 GHz and its metrological evaluation in order to be employed as a gas sensor. The prototype can be tailored towards a gas target by depositing an appropriate sensing layer of a nanostructured material. The sensor device is achieved by depositing the sensing material as film layer just on the gap of the resonator. Here, the analysis is focused on an Ag@α-Fe2O3 nanocomposite-based microstrip resonator used for sensing the relative humidity that is varied in the range from 0% to 75%. The increase of humidity value brings to a frequency shift in the two resonances observed in the measured reflection coefficient. The characteristics of the fabricated device suggest its promising use as humidity sensor.