Design And Testing Of High Frequency Structure Of Ka/Q Band Helix TWT

Helix TWT is widely used in electronic countermeasure,radar and communication,due to wide frequency band,high power and gain.With the development of military,communication and millimeter wave applications,the TWT with wide bandwidth and high efficiency are required to meet the needs of equipment.In this paper,the main research objective is to improve the electronic efficiency of TWT,while a Q-band(43~45.5GHz)narrow-band helix TWT and a Ka-band(26.5~40GHz)wide-band helix TWT are studied.The experiment of the high frequency structure of rectangular semimetallic rods is carried out,which is applied to the Ka-band helix TWT to meet the bandwidth requirements.In addition,the transmission characteristic of the slow wave structure and energy coupler of the Ka-band helix TWT is also tested.The main research methods,work contents and results of this paper are as follows:1.For Q-band helix TWT,by using HFSS to compare the high frequency characteristics of slow wave structure of rectangular and T-shaped dielectric rods,the slow wave structure of T-type rods with higher coupling impedance is chosen.Through the analysis on the high frequency characteristics of different parameters,the appropriate structure is designed.The beam-wave interaction of Q-band helix TWT is simulated by ORION.The best design of this TWT is obtained by comparing the output power and efficiency of different ways of pitch jump.The results show that when the negativepositive-negative pitch jump is used,the working voltage is 9930 V and the current is 88 mA,the gain in the working frequency band is more than 50 dB,and the output power and electronic efficiency are more than 170 W and 19%,respectively.2.In order to obtain a wide working bandwidth of Ka-band helix TWT,rectangular semi-metallic rods are used in the TWT,and the design scheme of slow wave structure and energy transmission devices of Ka-band helix TWT is obtained by calculation.The beam-wave interaction of the TWT is simulated with ORION software,and the power and electronic efficiency with different schemes of pitch jump,inner diameter jump or their simultaneous jump are discussed in this paper.The results on ORION show that the gain is higher than 42 dB,and the output power and electronic efficiency are more than 260 W and 20% respectively in the 26.5~40GHz band.And the physical phenomena in the process of beam-wave interaction are observed on CST.3.The experiment of slow wave structure,energy coupler and window of Ka-band helix TWT with semi-metallic rods has been processed,and the processing method of semi-metallic rods is mainly explored.The preliminary experiment results show that the standing-wave ratio is less than 2.7 in the frequency range of 26.5~40GHz,and further cold-test work is in progress.