Comparison of High Loss Liquid Dielectric Properties Measurement Using Waveguide and Resonator Methods

A comparison of experimental determination of the dielectric properties of high loss liquids using the microwave waveguide and resonator methods is presented. A differential microwave waveguide cavity for high loss liquids complex permittivity measurement in small volume has been designed and studied. This cavity consists of two circular waveguide cells with central rods made of quartz surrounded by high loss liquid under test. To eliminate complex propagation coefficient measurement errors due to diffraction effect on the ends of the layered waveguide cells, they have different lengths. We have measured the wave amplitude and phase coefficients for the waveguide cavity to estimate physical properties of a high loss liquid under test. A high Q–factor half-disk dielectric resonator with high loss liquid filling in a small hole has been studied as well. We have selected the water– ethanol solutions as a high loss liquid under test. We have determined the measurement sensitivity for these two techniques and discussed the results. The both studied waveguide and resonator methods can be used for complex permittivity determination of high loss liquids in small volume with comparable sensitivity.