Research On The Measurement Technology Of The Nonlinear Parameters Of The Travelling Wave Tubes

The travelling wave tubes(TWT) is an extremely important vacuum electronic device. It is playing important role in satellite communication, radar, electromagnetic countermeasure, etc. As a device, the TWT need some technical parameters to characterize its performance in order to evaluate whether the TWT is satisfy the design requirements or the application requirement. The technical parameters measurement of the TWT involved many microwave measurement technique and many microwave measurement instrument such as the VNA and the spectrum analyzer. Because the TWT is a device which used to amplify the high frequency signal. For the development and application of the TWT, there must be some reliable technical measures to test the related parameters accurately, which has become a key problem to be solved in order to promote the development of the TWT and promote the improvement of the measurement system. The project of our team has achieved the measurement system of the cold parameters and the essential device of the measurement system of the hot parameters. This dissertation gives the design scheme of the TWT nonlinear measurement system and the software platform of the Auto-test system based on previous work done by the senior. The following are the major work of this dissertation.Firstly, the measurement technology related to amplitude and phase has been researched in this dissertation. Two options was given to measure these parameters in this paper.One is data acquisition based on NET2801 of the six-port,the other is the VNA.The software platform was designed to achieve the Auto-switch of the measurement.The amplitude and phase measurement include the nonlinear of amplitude,the AM-PM,the 1dB compression point,etc.Secondly, the measurement technology related to spectrum has been researched. The Spectrum Analyzer is the main measure instrument used in this research. The output signal of TWT was sampled by the directional coupler and then send to the Spectrum Analyzer. The Spectral composition of the output signal can be obtained by it. The parameters related to the spectrum are the three order intermodulation, the noise power spectrum density, etc.Finally, the high power water load was designed and simulated. Its work frequency range from 2GHz to 18 GHz and it’s 11 of the simulation is below-20 dB. It has small volume and has no need of air cooling equipment. If the load could be machined successfully, the volume of the measurement system could be smaller.