Microwave Sensors for Permittivity Measurement of Solid Materials

This paper focuses on the development and testing of microwave sensors for measuring the permittivity of solid materials. We developed a sensor utilizing two CSRR resonators in a CPW technology and tested it with a solid material of fixed height (6 mm) and permittivity values ranging from 2.0 to 2.8. By varying the permittivity within this range, we observed the S21 parameter to detect frequency shifts, allowing us to study how changes in permittivity affect the sensor's frequency response. The results revealed a clear relationship between the material's permittivity and the frequency shifts observed in the S21 parameter. By analyzing these shifts, we derived an equation relating permittivity to frequency. This relationship enables the identification of specific solid materials based on their permittivity, providing a reliable and non-invasive method for permittivity measurement in various applications.