Frequency and phase locking of oscillators and magnetrons

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2018
Salur, Işıl
Phase control of oscillators is a method used to improve both frequency stability and phase noise. Despite magnetrons are simple and cost effective high power microwave generators, they suffer from frequency and phase instabilities. Therefore, array construction with magnetrons is a difficult task. Using injection locking method, phase control can be established, hence output stabilities of generators can be improved. As a result, output power signals of the locked magnetrons can be added in the radiation field without using a combiner. In this thesis, Adler’s injection locking theory is verified using a 300 MHz solid-state oscillator circuit with three locking configurations such as master-slave, peer-peer and self-locking. Phase and frequency locking is achieved for three cases. In the master-slave experiment, it is observed that phase noise of free-running oscillator, being locked to master oscillator, is improved about 11 dBc/Hz at 100 kHz offset. For peer-peer locking, an improvement of 3 dBc/Hz at 100 kHz offset and for self-locking, an improvement of 5 to 10 dBc/Hz at 100 kHz is observed according to the coaxial cable length. Observing the agreement between theory and application, an experimental setup for master-slave locking of two industrial magnetrons is proposed.