Whispering Gallery Mode Sapphire Resonator for Microwave Characterization of Lossy Liquids

Whispering gallery mode (WGM) resonators are used widely for electrophysical parameter determination of different substances. Earlier it was shown that radially two-layered resonator made of Teflon can be used for complex permittivity measurement of lossy liquids. The resonator was a Teflon ring sandwiched between conducting endplates (CEP). Substances measured were distilled water and ethyl alcohol. They were put into interior layer of resonator. It is worth to note that accuracy of lossy liquid (such as water) measurement by means of Teflon resonator is insufficient. Evidently, for increasing accuracy of complex permittivity measurement a complex permittivity of outer layer in the resonator must be higher than permittivity of Teflon.