Research On The Inhibition Of Backward Wave Oscillator And Harmonic Of Broadband TWT

Helix traveling wave tube(TWT) is a kind of microwave amplifiers widely used in modernization information equipment, such as radars system, communication and electron warfare because of wideband and high gain. The performance of helix Traveling wave tube will related to using effect of equipment, stability and reliability are very important to TWT, oscillation is the main factor which affect the stability of TWT. Oscillator contains reflection oscillation, backward wave oscillator and ? pattern Oscillation, backward wave oscillator is the main oscillator of helix TWT. Except the stability, the electron and wave interaction in TWT is nonlinear process, the output signal will include the input signal, the harmonic signals and the intermodulation signals, which will affect the output signal energy seriously and reduce the gain of TWT. So it is very necessary to study the backward wave oscillator and harmonics. In this paper, I made theoretical derivation and numerical simulation on 2-6GHz wideband helix TWT, study the helix TWT with attenuator and change the structure of high frequency to suppressin backward wave oscillator, then we hanve a preliminary study on harmonic injection. The main contents of this article are listed as the following:Based on the high frequency theory of slow-wave strcture whit attenuator, research attenuator impact on backward wave oscillator, we get the expression of dispersion and coupling impedance from cylindrical coordinate system, we use the TWT simulation software developed independently by Theory and Computer Simulation Laboratory of UESTC which named MTSS to simulate the location and the amount of attenuatior, research the impact on forward and reverse wave in 2-6GHz broadband TWT, which has positive significance for TWT design.Based on the theory of 1D nonlinear, numerical simulation 2-6GHz broadband helix TWT by MTSS, with the purpose of maintain flat dispersion curve and reducing the backward wave coupling impedance, study the varioue components of the high-frequency structural parameters such as the helix, three support poles and panels and wave action of backward wave coupling impedance, and compare the different impact of different structures to backward wave oscillator, so as to optimize the structure of the entire high-frequency and achieve adequate suppression backward wave oscillator.Focus on the influence of 2-6GHz broadband TWT output performance by harmonic injection method. Result show that the harmonic injection can suppress harmonic wave, we can the best input power and phase of harmonic wave, get the result that output power of basic tone and second harmonic with the variation of the power and phase of injected second harmonic wave.