High spectral purity microwave oscillator: design using conventional air-dielectric cavity.
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
Gupta
Amitava Sen
AS
National Physical Laboratory, New Delhi, India. sengupta@mail.nplindia.ernet.in
Howe
David A
DA
Nelson
Craig
C
Hati
Archita
A
Walls
Fred L
FL
Nava
Jose F
JF