Extraction and Analysis of the Resonance Properties of a Differential SRR-based RF Sensor

A radio-frequency (RF) sensor dedicated to characterize a small liquid volume is presented in this paper. In order to increase its robustness in regard to the ambient factors (as temperature, humidity, moisture, etc…), a differential configuration is adopted with a reference resonator that is loaded by a sample of well-known properties, whereas the sample under test is placed on the second resonator. However, depending on the similarity between the dielectric properties of the sample under test and the reference one, the properties of both resonances can be difficult to determine. The proposed post-processing method permits to extract the resonance parameters even for a strong overlap, increasing the reliability of the measurement interpretation.