On the Calculation of Biconical Cavity Parameters to Provide Up-To-Date Material Characterization

This paper describes approaches to biconical cavity eigenfrequency calculation. It is shown that the finite-element method loses accuracy only in the regions of a near-zero electric field (evanescent zones) at the ends of a biconical cavity. This, in particular, makes that method inapplicable to evanescent zone characterization, which is of importance in finding the dimensions of specimen insertion openings. The eigenfrequency shift with the insertion of dielectric specimens along the biconical cavity axis is presented as a function of the half-cone angle.