Hemispherical and aspheric WGM dielectric resonators with conducting plane: Radiation and conductivity losses in millimeter wavelength range

In this work, electromagnetic properties of a number of whispering gallery mode (WGM) dielectric resonators with conducting endplates are studied. They differ in the shape of the body of rotation. Radiation and conductivity losses are studied in Ka-band. For the hemispherical resonator the results of analytical calculation and experimental measurements of radiation losses are correlated, although the experimental values are higher compared with the calculated ones. Experimental data show that a resonator of a combined geometry, i. e. in the form of aspheric+cylindrical disk, is the most promising for surface impedance characterization of unconventional superconductors as well as for other types of conductors, which is important for contactless measurement of conductivity.