Research On Bandwidth Expansion And Efficiency Improvement Of High-band Traveling Wave Tube

With the increase of wireless communication capacity and the congestion of lowfrequency bands for communication,the future wireless communication spectrum will gradually expand to the high-band of millimeter wave and above.The high-frequency band can provide sufficient bandwidth and high-speed data transmission for communication,but the existing solid-state devices cannot provide the required output power under high-frequency working conditions,which limits their application in the millimeter wave field.Vacuum electronic devices can be fully used in the exploration of millimeter wave wireless communication systems due to their high-power advantages.This paper focuses on the research of folded waveguide traveling wave tubes in vacuum devices.The development of high-speed wireless communication technology brings development opportunities for folded waveguide traveling wave tubes,but also puts forward higher requirements for this.On the existing basis,in order to transmit data information as efficiently as possible,it is necessary to continue to further optimize and improve the working efficiency and working bandwidth of the device.The main tasks of this paper are:1.In-depth study of the one-dimensional nonlinear theory of the folded waveguide traveling wave tube,and obtain the phase information of the axial electron injection current and the electromagnetic wave electric field.By analyzing the phase difference information to reflect the beam-wave interaction process in the traveling wave tube,and giving reference to the design of the folded waveguide traveling wave tube.After that,it can be applied to the design of the phase velocity taper of the folded waveguide traveling wave tube.The simulation shows that the electronic efficiency and output power of the traveling wave tube have been effectively improved.2.Considering the requirements of communication devices for gain fluctuations in the working bandwidth,a three-segment folded waveguide traveling wave tube slowwave structure scheme is designed.The middle section uses the design method of enhancing the positive dispersion in the frequency band to move the best operating point from the low frequency of the working frequency band to the high frequency,which has the effect of improving the gain at higher frequencies and depressing the gain at lower frequencies.In the overall design,the middle section and the front and rear sections form a complementary effect to achieve gain balance in the frequency band and achieve the purpose of expanding the working bandwidth.3.Improve the design method of folded waveguide traveling wave tube.When optimizing problems,genetic algorithm has the advantage of being able to find and realize global optimization without considering the specific internal working mechanism of the problem,so this chapter focuses on how to introduce genetic algorithm into the design of folded waveguide traveling wave tube.According to the basic block diagram of genetic algorithm,the calculation program of wave beam interaction of one-dimensional folded waveguide traveling wave tube is rewritten,and the structural parameters of the wave tube high-frequency system are modified with the design goal of power improvement and bandwidth expansion.It has been verified that the optimized parameters have improved the overall performance of the traveling wave tube,and have made improvements in work efficiency and bandwidth.