Affiliations: College of Electronics and Information Engineering, Sichuan University, Chengdu, Sichuan, China
Correspondence:
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Corresponding author: Yang Yang, College of Electronics and Information Engineering, Sichuan University, Chengdu, Sichuan 610065, China. Tel.: +86 28 85408779; Fax: +86 28 85408779; E-mail:yyang@scu.edu.cn
Abstract: Magnetrons are widely applied to the rapidly developing
microwave industries as high power microwave sources. However, the
free-running magnetron produces unstable frequency and wideband spectrum,
which limits the magnetron's further applications for coherent
power-combining and scientific fields. In this paper, by introducing a
feedback loop with a high Q filter into the magnetron system, the output
frequency can be qusai locked around the center frequency of the filter if
the loop phase is between (2k-12)
π and (2k+12)π. Moreover, the output frequency bandwidth of
the self-injection magnetron is narrowed and the phase noise is also
reduced. In order to find out the requirements for the qusai locked
magnetron and the effects of the parameters on the qusai locked results, a
theoretical model based on the combination of the equivalent circuit of the
magnetron and the transfer function of the filter has been developed.
Furthermore, numerical analyses illustrate the effect of the loop phase, Q
value and the injection ratio on the output results. The experiments
validate the conclusions obtained in the theoretical analyses.
Keywords: Magnetron, self-injection, qusai locking, noise reduction, high Q filter
