Analysis And Experimental Research On Electromagnetic Characteristics Of Novel High Frequency System Working At Millimeter Wave Band

Millimeter wave and terahertz science and technology have become the focus of research in the field of electronic science,because they have wide and important application in many fields such as communication,biology,and medical treatment.The vacuum electronic device is an important radiation source that generates high-power millimeter waves and terahertz waves.With the increase of operating frequency and the limitation of device size-wavelength synchronization,the transverse size of highfrequency structure becomes smaller,and the difficulty of processing becomes higher and the transmission loss increases.Many novel high-frequency systems have been proposed to solve these problems.In order to estimate the influence of the novel RF structure on the working properties of the whole tube in advance,it's necessary to carry out the theoretical analysis and actual measurement of the electromagnetic characteristics of the high-frequency structure.This article focuses on the two novel millimeter wave devices,sine waveguide traveling wave tube and extended interaction Klystron(EIK)The high frequency characteristics of the main work and results are as follows:1.Based on the perturbation theory,the relevant formula are derived for measuring the RF characteristics of the traveling wave tube,and the corresponding experimental measurement methods are proposed.In addition,the experiments are also calculated in simulation software to obtain the dispersion characteristics and the coupling impedance value of the RF structure,verifying the derived measurement formula.2.The high-frequency structure of the G-band extended interaction Klystron based on the trapezoidal structure is designed through simulation.The simulation results show that the center frequency of the designed EIK is about 216.5GHz,and the maximum output power up to 115 W,gain 34.6dB,electronic efficiency 2.8% are obtained,when the working voltage is 18 kV,the beam current is 0.228 A,and the input signal is 40 mW,respectively.In the case of output power greater than 100 W,there is a bandwidth greater than 200 MHz,and the gain is greater than 33.9dB.Meanwhile,the model is simulated and measured by using the perturbation measurement theory,and its axial electric field distributions are obtained.This method can be used for the actual measurement on the high-frequency characteristics of an EIK.3.A set of platform on which high-frequency characteristic of the millimeter wave vacuum electronic device can be measured are designed and constructed,including motion control system,mechanical fixing system and measurement system.And the dispersion characteristics of W-band sine waveguide traveling wave tube are obtained by using this platform.The results show that the maximum error of the measured data and the simulated data is 1.17%,the minimum error is 0.39%,and the average error is 0.73%.The simulation results coincide quite well with the experimental data.Finally,the measurement error is further analyzed.