Application of a Calibration Technique for Broadband Dielectric Characterization Using a Narrowband Microwave Resonator Sensor

Microwave sensing has become a powerful tool for characterizing material properties, particularly in biomedical and material science applications. Among various microwave sensors, narrowband resonance-based sensors stand out for their high sensitivity, attributed to the strong field confinement they provide. Traditionally, the analysis of dielectric properties using resonance-based microwave sensors is restricted to a single frequency of operation. However, the scattering parameters measured by these sensors contain information over the entire frequency range, which can be leveraged for enhanced material characterization. In this work, we demonstrate the application of a calibration technique to an interdigitated electrode (IDE)-based microwave resonator sensor operating in the 3.5-4 GHz range. By deembedding two-port measurements, the sensor accurately retrieves the complex permittivity of materials under test (MUT). The technique was validated using ethanol-water mixtures (60 %, 70 %, 80 %, and 90 % ethanol), where different combinations of three samples enabled the characterization of the fourth sample. The retrieved permittivity values showed good agreement with commercial coaxial probe measurements. This study highlights the potential of applying this calibration approach to novel microwave sensor designs, expanding their utility for high-precision, broadband material characterization.