| 摘要 |
<p>A microwave oscillator suitable for millimetre wavelengths comprises a Gunn diode (3) coupled to a wavelength (1) by a resonant-cap structure (5,6). The diode (3) generates microwave energy both at a fundamental frequency fo which is below the cut-off frequency of the waveguide (1) and at a second harmonic frequency 2fo above cut-off. To control the generation of microwave energy at 2fo, energy at fo may be coupled into the waveguide (1), e.g. from an adjacent further waveguide (9) above its cut-off, by means of an electric probe (8) extending close to the cap (5). The probe (8) may couple in a locking signal at or close to the free-running value of fo from another oscillator having better noise performance and electronic tuning, thereby locking 2fo to twice the frequency of the locking signal, or alternatively may couple to a varactor-tuned cavity resonant at fo.</p> |
