Improved Injection Locking of Microwave FM-Oscillators

A system for injection locking by angle-modulated signals is presented in which both the locked oscillator and the locking source is angle-modulated by the same signal. This method provides increased locking gain and improved stability against oscillator drift with preserved signal performance. Intermodulation measurements on a low-Q Gunn-oscillator, angle-modulated by a weakly coupled varactor (0.5 dB loss) demonstrated the expected effects.