A simple calibration-free method of complex permittivity extraction

Here we present a new calibration-free method for relative complex permittivity extraction, which allows using accessible and cheap materials and simplifies the measurement process. The method combines the advantages of resonant and non-resonant techniques and provides results for liquids and solids in 0.5-5GHz frequency band in dependence on the material type. The essence of the proposed method is based on measuring of the magnetic dipole resonance of a spherical sample. The size of such a sphere can be dynamically changed making it possible to evaluate its permittivity at different frequencies. Mie theory serves as the basis for connecting the resonant frequency of the sample with the real part of the permittivity, while imaginary part can be found from Q-factor. In this work we demonstrate the efficiency of the method for water. In addition, we evaluate the applicability of the method for lossy materials.