Radially two-layered quasi-optical dielectric resonators with ethyl alcohol and water

Two-layered (along a radius) quasi-optical dielectric resonators of Teflon with conducting endplates and lossy liquids are studied in Ka-band. Whispering gallery modes are excited in the resonators. The measurement data are compared with theoretical calculations of frequencies and Q-factors of the resonators filled with water, ethyl alcohol and benzine. A number of the "anomalies" of the resonators are explained in terms of change of field distribution in such resonators. Availability of the resonator for microwave characterization of lossy liquids from first principles (i.e. without calibration procedure) is considered. The QDR-based technique can be important also for measurement of reference liquids in millimeter wavelength range.