Ultra-Low-Noise Cavity-Stabilized Microwave Reference Oscillator Using an Air-Dielectric Resonator

C.W. Nelson, D. A. Howe, A. Sen Gupta

Abstract:	Ultra-low-noise microwave oscillators are often required to serve as reference signals in precision phase modulation (PM) noise measurement systems and in a host of other applications. We have significantly improved the spectral purity of NIST’s traditional cavity-stabilized microwave oscillator design, which uses a conventional air-dielectric cavity resonator as a frequency discriminator. We developed and tested an accurate model of the expected PM noise that indicates, among other things, that a conventional air-dielectric resonator of moderate Q will exhibit less discriminator noise than more esoteric and expensive dielectric resonators tuned to a high-order, high-Q mode and driven at the dielectric's optimum power. Additionally, we increase the discriminator's intrinsic signal-to-noise ratio by use of a high-power carrier signal to interrogate an optimally coupled cavity, while the high level of the carrier is suppressed before the phase detector. We report exceptionally low PM noise levels from a microwave oscillator operating at 10 GHz.
Published in:	Proceedings of the 36th Annual Precise Time and Time Interval Systems and Applications Meeting December 7 - 9, 2004 Hyatt Regency Washington on Capitol Hill Washington, D.C.
Pages:	173 - 178
Cite this article:	Nelson, C.W., Howe, D. A., Gupta, A. Sen, "Ultra-Low-Noise Cavity-Stabilized Microwave Reference Oscillator Using an Air-Dielectric Resonator," Proceedings of the 36th Annual Precise Time and Time Interval Systems and Applications Meeting, Washington, D.C., December 2004, pp. 173-178.
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