Research On Traveling Wave Tube Applied In Ka Band Microwave Power Module

Microwave Power Module(MPM)is a new power amplifier.MPM has the advantages of high output power,high efficiency of Traveling Wave Tube(TWT)and miniaturization,low noise of Solid-state Power Amplifier.Microwave Power Module has important value in military and civil fields because of its excellent characteristics.At present,helix slow-wave structure is widely used in Microwave Power Module in microwave frequency band.It has the advantages of wide bandwidth and high efficiency.When working in millimeter-wave band,helix slow-wave-structure will become very small due to size co-transition effect.At this time,not only helix,but the circular beam electron gun will face processing difficulties.Therefore,in millimeter wave band,planar slow wave structure which can be applied to band beam electron gun has attracted great attention all over the world in recent years.This kind of slow-wave-structure a natural band beam channel.The electromagnetic wave is transmitted in the form of surface wave in this slow-wave structure so that it does not need to consider the separation of electron beam signal and electromagnetic wave.With the development of band-beam electron gun and the miniaturization of Traveling Wave Tube,this planar slow-wave structure has considerable market application prospects.This kind of slow-wave structure based on planar microstrip transmission line has a great impetus to the miniaturization of TWT.In this paper,the microstrip slow-wave structure is studied in detail from the aspects of computer simulation and processing measurement.It is proposed that the microstrip slow-wave structure can be used as the first stage amplifier,and then Ka-band staggered double-grid traveling wave tube is designed as the secondary amplifier,so that the Millimeter-wave Power Module can have a larger power output in Ka-band.The main contents of this paper are as follows.(1)A Ka-band U-shaped planar SWS supported by diamond dielectric rods TWT is designed.The main work is as follows: firstly,analyzing high-frequency characteristics,secondly designing ridge waveguide import and output structure to make it transition to standard waveguide port BJ320,then calculating the transmission characteristics of the slow-wave structure,and then calculating the beam-wave interaction.In the simulation results,it can be concluded that in the band range of 32-38 GHz,the peak output gain can reach 17.04 dB and the peak output can reach 57 W.Finally,the whole slow-wave structure is processed,assembled and tested for transmission characteristics.(2)Based on the TWT introduced in chapter 2,an electronic optical system that meets its requirements is designed.Firstly,based on Pierce Electron Gun Theory,the band-beam electron gun is designed.Then the Periodic Cousped Magnet System(PCM)is designed to ensure the progress of beam-wave interaction and the passage of electron beam through slow-wave structure(3)Designing a Ka-band staggered double-grating traveling wave tube is to further amplify the electromagnetic signal.The simulation result shows that the reflection coefficient is generally lower than-15 dB in the frequency band of 34-37 GHz.The beam-wave interaction shows that the peak output power can reach 550 W and the electronic efficiency is 9.96%.