Precise dielectric measurekents at 68.5 GHz using an open resonator

An open resonator dielectric measurement system working in the vicinity of 68.5 GHz has been constructed. It employs a frequency-swept klystron as its source. The signal is detected through a triple-freq ency harmonic mixer. The measurement error of l/sub r/ is shown to be of the order of 10/sup -3/ and that of tan less than 5x10/sup -5/. And measurements have been made for FTFE, fused silica and TFX.