Ultra-low Noise Cavity Stabilized Microwave Reference Oscillator using an Air-dielectric Resonator

Published

December 7, 2004

Author(s)

Craig Nelson, David A. Howe, A Sen Gupta

Abstract

Ultra-low noise microwave oscillators are often required to serve as reference signals in precision 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.

Proceedings Title

Proc. PTTI

Conference Location

Washington, DC, USA

Conference Title

Precise Time and Time Interval Planning and Applications Meeting

Pub Type

Conferences

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Keywords

cavity stabilized, frequency standard, microwave, oscillator, phase noise

Citation

Nelson, C. , Howe, D. and Sen Gupta, A. (2004), Ultra-low Noise Cavity Stabilized Microwave Reference Oscillator using an Air-dielectric Resonator, Proc. PTTI , Washington, DC, USA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=30055 (Accessed October 17, 2025)