OHMIC SELECTION IN OPEN COAXIAL RESONATORS - AN EXPERIMENTAL-STUDY

A study of ohmic selective properties of open coaxial cylindrical reso nators has been conducted experimentally and compared with theory. The resonator consists of an inner cylinder made of silicon carbide symme trically located inside an outer cylindrical, tube shaped waveguide. S everal fundamental TE modes were identified over the range 9 to 17 GHz through measurements of the resonant frequencies and the associated q uality factors. Mode discrimination is achieved both by exploring sele ctive ohmic effects and examining the electrodynamical properties of t he coaxial cylindrical waveguide. The effectiveness of a silicon carbi de coaxial insert in providing ohmic mode selection is demonstrated in that the total Q factors of TE(mp) modes with radial index p greater- than-or-equal-to 2 become well below the quality factors for surface T E(ml) modes. It has been verified that both structure and number of re sonant modes are strongly dependent on the diameter and the resistivit y of the coaxial insert.