An Accurate Radially Stratified Approach for Determining the Complex Permittivity of Liquids in a Cylindrical Microwave Cavity

A complex permittivity measurement method is introduced that is applicable to radially stratified resonant microwave cavities excited by a TM_0m0 eigenmode. This single-frequency approach is well suited to the measurement of the complex permittivity of liquids because it can accurately account for a supporting tube container. It can also be applied advantageously to solid rods or tubes. The frequency dependence, as well as the field configuration at the cavity walls are taken into account more accurately than in other approaches. Comparing our results with published measurements of well-known liquids validates this technique.