| In recent years, the vacuum microwave electronics research scholars haveconcentrated on a new type of slow-wave line structure-(tortuous waveguide) foldedwaveguide slow wave line. The new type of slow-wave line has an all-metal structure,which has the advantage of power and bandwidth. A millimeter-wave evensubmillimeter small radiation source can be made by this folded waveguide travelingwave tube. With the rapid development of high-power microwave vacuum devices, thefolded waveguide millimeter-wave traveling wave tube with bandwidth, has beenwidely used in military, satellite, telecommunications and other areas. Thecommunications, radar and satellite data relay from oversea has been extended to the Qband folded traveling wave tube. Compared with the other band traveling wave tubes,this band signal has strong anti-interference ability, and can not be intercepted, whichcan greatly enhance the security of military electronic equipment, communicationssystems. However our country made a lot of research in this band, but our research can’tachieve wide bandwidth, high power output, which can not meet the needs of themodern military. It can be seen that Q-band traveling wave tube study has importantpractical significance.According to the development of Q band traveling wave tube slow, this paperdesign a folded waveguide traveling wave tubes work in43.5GHz-45.5GHz，theefficiency of the whole working band is about25%, the output power is up to150W, thewhole tube gain more than30dB, The main contents of this article:1. According to the Q-band folded traveling wave tube operating parameters, suchas the working voltage of the electron gun, the current, and the surface of the cathodecurrent density, we can calculate the appropriate size of the electron gun. We use theUkrainian software ORION simulation and optimization a suitable electron. The rangeof this electron gun more than20mm and the waist radius is about0.2mm.2. According to the frequency of the folded waveguide traveling wave tube, wedesigned a slow wave line structure to meet the traveling wave tube, And analyzed theeach size of the slow wave line has influence on high-frequency characteristics. We made high-frequency characteristics incorporate into the ORION software, and use theORION simulation the wave interaction. The simulation shows that the output powerand the gain of tube are more than expected, which Show the rationality of the slowwave line design. In this process we need to be patient to optimization the size of theslow-wave line, and in the optimization process we need to consider the slow-wavelinear dispersion characteristics and coupling impedance, to get the right size of theslow wave line.3. According to the parameters of the electron gun voltage and the electron beamradius to design permanent magnetic focusing system (PPM), and estimate the otherdimensions by determining the PPM cycle L and the axial magnetic field strength.Simulation and optimization the PPM in FEMM software, and test and verify themagnetic field strength in the electron beams, the simulation result shows that theelectron beam has a good laminar and a small envelope fluctuation, which illustrates thefeasibility of the present design.4. Design a suitable new input and output structure and concentration of theattenuator. Use the HFSS software designed and optimized the input-output structureand attenuator, made their voltage standing wave ratio can be less than about1.5.5. Assembled the designed device, and tested the circulation rate, output power,gain, and other parameters of the folded waveguide traveling wave tube.6. Summarized the above work, and pointed out that the main work of this paper.Gave the recommendations of the further research work. |
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