Application of the body of revolution finite-element method in a re-entrant cavity for fast and accurate dielectric parameter measurements

In dielectrometry, traditional analytical and numerical algorithms are difficultly employed in complex resonant cavities. For a special kind of structure (a rotating resonant cavity), the body of revolution finite-element method (BOR-FEM) is employed to calculate the resonant parameters and dielectric parameters. In this paper, several typical resonant structures are selected for analysis and verification. Compared with the resonance parameter values in the literature and the simulation results of commercial software, the error of the BOR-FEM calculation is less than 0.9% and a single solution time is less than 1 s. Reentrant coaxial resonant cavities loaded with dielectric materials are analyzed using this method and compared with simulation results, showing good agreement. Finally, in this paper, the established BOR-FEM method is successfully applied with a machined cavity for the accurate measurement of the complex dielectric constant of dielectric materials. The test specimens were machined from polytetrafluoroethylene, fused silica and Al2O3, and the test results showed good agreement with the literature reference values.