Stability measurements of microwave frequency synthesis with liquid helium cooled cryogenic sapphire oscillators

摘要

We report on the evaluation of microwave frequency synthesis using twocryogenic sapphire oscillators developed at the University of WesternAustralia. A down converter is used to make comparisons between microwaveclocks at different frequencies, where the synthesized signal has a stabilitynot significantly different from the reference oscillator. By combining the CSOwith a H-maser, a reference source of arbitrary frequency at X-band can besynthesized with a fractional frequency stability of sub-$4 \times 10^{-15}$for integration times between 1 s and 10,000 s.