A Precision Resonance Method for Measuring Dielectric Properties of Low-Loss Solid Materials in the Microwave Region

A precision resonance method for measuring the dielectric properties of low loss solid materials has been developed in our laboratory. The dielectric sample to be measured is shaped into a cylindrical disk and inserted into a cylindrical cavity resonator oscillating in the T10y mode. ϵ can be measured from the difference between the axial lengths of the cavity tuned to the same frequency with and without the sample, and tan δ can be found from the difference between the Q's of the cavity with and without the sample. By making use of a special marker of a resonance point on an oscilloscope, the measurements accuracy can be improved to yield only 1 per cent error in ϵ and 3 per cent error in tan δ for various low-loss samples. Such materials as polystyrol, polyethylene, teflon, and glass for high-frequency use were tested at 4,000 mc, 9,000 mc and 24,000 mc.