Uncertainty analysis of Q-factor measurement in cavity resonator method by electromagnetic simulation

Abstract

Effects of cavity material on the Q-factor measurement of microwave dielectric materials were studied by HFSS simulation and the measurements using metal cavity. TE01δ mode resonant frequency was determined from the electric and magnetic field patterns and the Q-factor was calculated from the 3 dB bandwidth of resonant peak at the scattering matrix S21 spectrum. In the cavity resonator method, Cu metal cavity has been generally used. However, the oxidized surface of Cu cavity could generate errors in Q-factor measurements. From the simulation, it is observed that the Q-factor significantly decreased with decreasing conductivity of cavity metal. When the conductivity of the oxidized Cu is assumed as 1000 Ω−1 m−1, the Q-factor could be decreased by 80% compared to pure Cu.