Minimum Frequency Noise in Oscillators Applying an Overcoupled Cavity

Frequency noise in oscillators can be reduced by circuit methods. According to our recent results, a significant reduction in frequency noise has been achieved by an overcoupled cavity. In comparison to a single cavity oscillator, the noise reduction is 10 dB with kQ2=2, and 23 dB with kQ2=5. In the experiments with a coupled cavity Gunn oscillator, an FM signal-to-noise ratio of 85 dB has been attained using visometric weighting.