Technique for improving the frequency/temperature characteristics of 3cm-band Gunn oscillators

A Gunn oscillator was used to stabilise another by injection locking. Over an ambient temperature range of +50 to ?20°C, the frequency drift of ?0.46 MHz/degC was reduced to +1.4 kHz/degC. The practical limit to the stability is set by changes in the pulling of the control-source frequency, but some improvement is possible by increasing the isolation between the oscillators.