A Coaxial Resonator in a Circular Locked Mode Waveguide to Study the Influence of Copper Surface Modification on Its Conductivity

A resonator on a locked mode in a transcendental (evanescent) waveguide is presented. The resonator contains a segment of a cylinder mounted in a circular waveguide coaxially with its inner surface. The electromagnetic field was localized near the cylinder and a resonance was excited at a frequency of 4 GHz on the TEM oscillation mode. The cutoff frequency for the lowest ТЕ₁₁ mode in the selected waveguide was ~7 GHz; therefore, at lower frequencies, the electromagnetic wave could not propagate along the waveguide and the locked TEM mode was implemented. The main losses are concentrated in the cylinder, thus making it possible to use this resonator to study the effect of modification of the cylinder surface on its Q factor. The paper describes the method of using such a resonator for this purpose and presents the results of a study of the effect of annealing and graphene coating of the copper surface on its properties. Graphene was synthesized on copper by the method of chemical deposition from the gas phase (CVD).