title: High spectral purity microwave oscillator: design using conventional air-dielectric cavity.
abstract: We report exceptionally low PM noise levels from a microwave oscillator that uses a conventional air-dielectric cavity resonator as a frequency discriminator. Our approach is to 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 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 in this approach than do more esoteric and expensive dielectric resonators tuned to a high-order, high-Q mode and driven at the dielectric's optimum
authors.affiliation: National Physical Laboratory, New Delhi, India. sengupta@mail.nplindia.ernet.in
authors.forename: Amitava Sen
authors.initials: AS
authors.lastname: Gupta
authors.forename: David A
authors.initials: DA
authors.lastname: Howe
authors.forename: Craig
authors.initials: C
authors.lastname: Nelson
authors.forename: Archita
authors.initials: A
authors.lastname: Hati
authors.forename: Fred L
authors.initials: FL
authors.lastname: Walls
authors.forename: Jose F
authors.initials: JF
authors.lastname: Nava