Characterization of the Q-factor of resonator for dielectric measurements

The transmission-type measurement of the Q-factor of a reentrant cavity is used to determine unloaded Qu from the measured loaded Ql by the 3 dB three frequencies method together with insertion loss at the maximum output. Also, the one-port reflection technique is used to determine unloaded Qu from the resonant frequency and the bandwidth measured at the xdB point, as well as the magnitudes of the input reflection coefficient measured at both resonant frequency and xdB return loss for the same reentrant cavity. The arithmetic mean Qu was evaluated to be 2519±34 tested under the 40 various couplings at frequency 500 MHz by using transmission and reflection techniques. Finally, these techniques are applied to the realization and tuning of that the input and output couplings are identical to each other for a transmission-mode resonator. Meanwhile, the selection of Q-factor values in measurements of complex permittivity of dielectric materials is discussed.