Research On W-band Banding Electron Injection Microstrip Meander-Line TWT

At present,microwave devices are developing in the direction of high frequency,high power and miniaturization.Although solid-state electronic devices have a dominant position in the low-frequency field,they have disadvantages such as low power and narrow bandwidth in high-frequency applications;although vacuum electronic devices have high power and wide operating frequency bands,they are bulky and difficult to process.The planar traveling wave tube has the advantages of small size,high efficiency,wide frequency band,easy processing,and has the advantages of both,which is an important research direction of vacuum electronics.Therefore,it is of great significance and value to carry out research on the folded microstrip line traveling wave tube and provide technical support for the new type of traveling wave tube.The main research contents of this thesis are as follows:(1)A W-band U-shaped microstrip line traveling wave tube with diamond medium as support rod is designed.Firstly,the electromagnetic properties of the W-band microstrip line slow-wave structure are studied by using HFSS and CST electromagnetic simulation design software,and then the injection-wave interaction is studied by PIC particle simulation.The simulation results are:in 86 GHz-90 GHz,S₁₁ is less than-15 d B,S₂₁ is-8 d B on average,the gain reaches the maximum at 88 GHz and 89 GHz,and the voltage increases by ₁₁ times,that is,the maximum power gain is 20.8 d B.(2)On the basis of the above research,explore the realization of a microstrip line traveling wave tube with multi-channel signal output.The simulation results of the traveling wave tube:within 93 GHz-97 GHz,S₁₁ is less than-15 d B,S₂₁ is-8 d B on average,and at 95.5 GHz The gain reaches the maximum,and the voltage increases by 7times,that is,the maximum power gain is 16.9 d B.(3)According to the requirements of the W-band U-shaped microstrip line traveling wave tube,the supporting electron optical system is researched,and the strip-shaped electron gun is designed to emit electrons of specific shape and current,and then the periodic permanent magnet focusing system(PCM)is designed.The electron beam trajectory is controlled to ensure the effective progress of the beam-wave interaction.(4)Finally,the processing and assembly experiments were carried out,and the processing technology and assembly technology of the folded microstrip line traveling wave tube were explored and studied.First,the box-shaped window of the W-band is processed and measured,and the test results are matched with the simulation.Secondly,the EDM technology and femtosecond laser cutting technology were used to process the slow-wave lines,and sputtering copper plating and electroplating copper were used to realize the copper layer on the surface of the slow-wave lines,and the advantages and disadvantages of each process were compared and analyzed.Finally,the finished product is tested,and the test result is quite different from the expectation.The reason analysis and improvement plan are given in this thesis.