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AssigneeU.S. Philips Corporation
InventorsStuart M. Feeney, David H. Evans, Kenneth Holford
Estimating the term…
In addition to a first opening (11) forming a primary output from a waveguide cavity (10) of a microwave oscillator, a coupling aperture (12) in a reflective wall (32) provides a secondary output which does not degrade the performance or tuning characteristics of the source. Less than -20 dB of the source power may be coupled out via the aperture (12) and is used in a feed-back loop (12,21,23,24,36) with an harmonic mixer (21) and frequency discriminator (24) to stabilize the source. The mixer comprises a further waveguide section (15) separated from the source cavity (10) by the reflective wall (32). An advantageous mixer assembly comprises a circuit substrate which is mounted across the further waveguide cavity (15) and which carries an inductive probe by which the signal from the coupling aperture (12) is fed to an antiparallel pair of mixer diodes on the substrate. The whole assembly may be bolted together through holes (34).
A microwave oscillator comprising a waveguide forming a source cavity separated from a detector section by a reflective wall, an oscillator device mounted in the source cavity for generating power of a desired microwave frequency, the wall being present at one end of the source cavity for reflecting the microwave power generated by the oscillator device, a first opening being present in another wall portion of the source cavity to provide a primary output of the microwave power, a coupling aperture being present in the reflective wall to provide as a secondary output a sample of the microwave power from the source cavity to the detector section, detector means associated with the detector section for generating from the sample a signal indicative of whether the desired microwave frequency is being generated in the source cavity, and a bias terminal to the source cavity for applying a bias signal for controlling the microwave power generated in the source cavity, which oscillator is characterised in that the detector means is a mixer mounted in the detector section of the waveguide for mixing a stable reference with the sample from the coupling aperture and thereby generating a frequency signal which comprises any error in the oscillator frequency from the desired frequency, and a frequency discriminator is coupled in a feed-back loop between the mixer and the bias terminal for providing a corrective bias signal regulating the frequency of the oscillator in accordance with the frequency signal generated by the mixer.
Dependencies are inferred from the claim text.