Modeling and Experimental Studies of Magnetron Injection Locking

Summary form only given. A set of differential equations has been developed from an equivalent-circuit model for a general oscillator, to explain qualitatively the lock-in process observed during an injection locking experiment between two standard oven magnetrons in a master-slave configuration. Both time- and frequency-domain solutions of the system are considered. The time-domain solution yields growth and saturation behaviors of the signal, as well as the familiar Adler's condition with a small modification by the frequency pushing effect. The frequency-domain solution gives the frequency response as the driver's frequency is tuned around the oscillating frequency. The injection-locking experiment is built using two CW microwave oven magnetrons. The driver and the oscillator are 2.45 GHz, 800 W, National Electronics magnetrons, operated using two ASTEX power supplies. The main part of the microwave power produced by the driver magnetron is dissipated into a water load, while a small fraction, controlled using tuning stubs, is injected into the oscillator magnetron for phase and frequency locking. Experimental diagnostics include power, microwave spectra and phase noise measurements. The injection locking mechanism observed experimentally by varying the injected power level was recovered qualitatively in our numerical results, from general oscillator theory. In addition, experimental injection locking has been demonstrated at drive power levels in accordance with those suggested by Adler's condition