Measurement of microwave dielectric properties of low loss diamond film at Ka band using the split-cylinder resonator method

The excellent properties of diamond films make it extremely attractive to apply the material in microwave vacuum devices, in particular in high-power conditions. However, low dielectric loss and small thickness (usual less than 0.5mm) of the material make it difficult to measure its microwave dielectric properties. In this paper, we describe construction of a split-cylinder resonator and application of the apparatus in measuring dielectric properties of a diamond film, together with a sapphire and a single-crystal quartz thin film sample at Ka-band. Results show that the split-cylinder resonator could meet the requirement to measure microwave dielectric properties of low loss thin film materials such as diamond films.