Conductivity measurement in mm-wave band with a Fabry-Perot open resonator

This paper presents nondestructive conductivity measurement in the 20-40 GHz range with a Fabry-Perot open resonator, which is already known for its applicability in the characterization of low-loss dielectric laminates. In the presented setup, no electromagnetic model is needed to determine unknown conductivity of the material. The only figures of merit are Q-factors of the empty resonator and the one loaded with the sample. It is shown that the plano-concave open resonator can be used in the measurement of conductivity ranging from 10^4 up to a few 10^7 S/m.