L-band Magnetron Phase Locking And Power Combining Technology Research

Phase locking technology is used in magnetron system which can make the magnetron woks in dot frequency, thus it is benefit for the power combination of several magnetrons. Accroding to the operating principles of the magnetron, a 1575MHz magnetron has been designed. The free and phase locking oscillations are simulated by using simulation software. The result shows, when it is free oscillation, the output power is 32kW and the efficiency achieves 76%. It has made some theoretical analysis and numerical calculation to the phase locking technology for high-power microwave tube, then analyzes the characteristics and different phase locking methods. Injection phase locking has a short phase-locked time but less bandwidth. Phase locking loop has a long phase locking time. However injection/phase locking loop has both of the advantages and meets the requirements. With injection/phase locking loop method, the experiments of power combination have proved the feasibility of above options.First experiment tests the feasibility of phase locking for single high power magnetron. By entering an injected signal whose power and frequency are definite, the frequency of the magnetron can achieve locking state. It was found that: 1) the larger excitation source, the more wide-bandwidth phase-locked; 2) the smaller power-supply ripple, the more bandwidth of the phase-locked magnetron; 3) different types of phase locking magnetron have different characteristics; 4) by changing the magnetron magnetic field, it can expand the magnetron phase locking bandwidth.Coupling part of the signal from the first phase locking magnetron system into the second magnetron system makes the second one achieve phase locking state. Experiment confirmed that this method can simultaneously lock two signals. Two small signals coupled from both phase locking magnetron systems are combined with a 3dB power splitter. What's more, when the injection frequency is 2437~2444MHz, the combination efficiency is no less than 70.8% and the maximum combination efficiency is about 96.2 %( 2444MHz).The experiment shows that: The investigation of phase locking has been done to single magnetron and double magnetrons, and two cases both can reach the locking states. Then, a power combination has also been made to both magnetrons by the phase locking method, the result shows well.