Dielectric sleeve resonator techniques for microwave complex permittivity evaluation

Closed-form analytical solutions are derived for accurate microwave dielectric characterization of rod test specimens inserted into dielectric sleeve resonators placed centrally in a metal cavity. Low-loss sleeve resonators can be used advantageously for multiple frequency measurements of the same specimen and may be employed for accurate dielectric characterization of high-permittivity specimens having dielectric loss factors greater than 0.001. Uncertainty relations for permittivity and dielectric loss are also shown, which demonstrate that when sample electric energy filling factors are greater than 0.4, relative uncertainties in measured permittivity and dielectric loss tangent are less than 1% and 4%, even for relative permittivities greater than 600. Example measurements are given that illustrate how this dielectric resonator system can be employed for dielectric characterization of ferroelectric materials at temperatures both near or far from their Curie temperatures.