Some discussions of the resonator structure for the cut-off waveguide method and the round robin test

A novel structure of a circular cylindrical resonator for the cut-off waveguide method are proposed to suppress unwanted TE modes in the axial direction and TM modes in the radial direction, respectively. Moreover, the round robin test is performed by using seven copper cavities and three low loss dielectric plates. It is verified numerically and experimentally that the novel structure of the resonator is useful to suppress the unwanted resonance modes. Moreover, it is found that the measurement accuracies of this method are estimated within 1 percent for ε_r and within 15 percents for tanδ.