Theoretical investigation of frequency characteristics of free oscillation and injection-locked magnetrons

The frequency characteristics of free oscillation magnetron（FOM） and injection-locked magnetron（ILM） are theoretically investigated.By using the equal power voltage obtained from the experiment data,expressions of the frequency and radio frequency（RF） voltage of FOM and ILM,as well as the locking bandwidth,on the anode voltage and magnetic field are derived.With the increase of the anode voltage and the decrease of the magnetic field,the power and its growth rate increase,while the frequency increases and its growth rate decreases.The theoretical frequency and power of FOM agree with the particle-in-cell（PIC） simulation results.Besides,the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results,which verifies the accuracy of the theory.The theory provides a novel calculation method of frequency characteristics.It can approximately analyze the power and frequency of both FOM and ILM,which promotes the industrial applications of magnetron and microwave energy.

Theoretical design and analysis of high-gain over-moded microwave pulse compression system

Purpose In the research of the microwave pulse compression,it was found that a new physical model has a high power gain for the rectangular TE_(1,0,20) resonant mode at 2.920 GHz in S-band than the traditional physical model.In this report,the model structure,physical principle,simulation results,and theoretical analysis will be given in detail.Methods In the new physical model of microwave pulse compression system,(1)the technologies of the over-moded resonant cavity and over-sized output waveguide were used together first time for the rectangular TE_(1,0,20) resonant mode at 2.920 GHz in S-band,in order to improve the Q-value of the microwave resonant cavity and increase the power gain of the output pulse;(2)optimize the dimensions of the coupling window to get the maximum efficiency of the energy storage in the resonant cavity.Results From the latest research,it was shown that,in the optimal resonant state,(1)the power gain of the system can reach up to 276.97.Relative the traditional physical model,the power gain increased by 53.40%;(2)in the optimal resonant state,the energy storage efficiency of the over-moded system has also reached up to 88.91%.Relative to the traditional physical model,the efficiency increased by 23.33%;(3)another important result is that the power gain is very sensitive to the deviations of the resonant cavity length and output waveguide position from their optimal values.For example,the power gain will decrease by 61.45 or 67.17%,if the length deviation of the resonant cavity is−0.10 mm or+0.10 mm.It is very important to the theoretical and experimental studies.Conclusion It was shown that the new physical model of microwave pulse compression system has a higher power gain than the traditional physical model,by using the over-moded technology to the resonant cavity and output waveguide.Because of the universality of this high-gain over-moded physical model,the high-gain over-moded technology can be applied directly to X,Ku,and Ka bands.