Study On X-band Ring-loop Structure Traveling Wave Tube

As the heart of military equipment such as radar,communication and electronic countermeasure,helix TWT has become the key microwave power amplification in many equipments with its characteristics of high power,wide frequency band,high efficiency,and so on.However,as the frequency increases,the backwave oscillator become more serious and it is hard to achieve high power.This thesis studies the Ring-Loop,which is suitable for the development of high frequency and high power TWT.The Ring-Loop has high coupling impedance and large gain for per unite length,which can meet the requirements of TWT miniaturization.Its unique loop structure can increase the coupling impedance and suppress the backwave oscillation.However,it is difficult to process such a slow-wave structure and there is no intuitive understanding of the Ring-Loop.In this paper,the excellent performance of the Ring-Loop is studied.The main content and innovation points of this dissertation are as follows:1.CST was used to calculate the dispersion characteristics and coupling impedance of the Ring-Loop.The simulation results showed that the loop structure could reduce the phase velocity and increase the coupling impedance.Based on the analysis of the surface current and vertical field distribution for the Ring-Loop,the mechanism of high coupling impedance is obtained.2.In X-band,scan and analyze the geometric size of the Ring-Loop.Get the carve of dispersion characteristic and the impedance,and obtains the general rule.3.The result of MTSS shows that the star-oscillating current and length of the Ring-Loop are more than twice that of the helix.This paper studies the inhibitory effect of the width and the height of the loop on the backwave oscillation and obtains the general rule.4.The actual measurement showed that the operating voltage of the Ring-Loop TWT was reduced from 15 kV to 14 kV,and the center frequency is shifted to a low frequency by 1 GHz.