Research Of The High Power And Passive Tuner

With the improvement of science and technology and the progress of information industry, high-power microwave devices are more and more applied to the microwave system, so the test results of high-power microwave semiconductor device also be required a relatively high accuracy in the development and application. Not only device producers must study how to accurately measure the parameters of devices, but also users want to be able to get accurate parameters of devices, especially in the case of high-power. Tuner is an essential part of this high power testing system.This paper mainly described the basic principle and design process of the high-power passive automatic tuner, the device is the core component of high-power automatic test system, DUT can be directly tested by the designed tuner based on load-pull technique at high power situation. Obviously, the performance of high-power passive automatic tuner directly determines the entire automated test system. Used coaxial waveguide as the main structure to achieve the frequency band from 6 GHz to 18 GHz; the changes of slider structure in the horizontal position and vertical position affect the Voltage Standing Wave Ratio and phase constant parameters of tuner; used the horizontal and vertical movement of the motor to drive the slider to automatically allocate; displacement sensors is used to accurately locate the position of the slider and form a closed loop state with the motor; the voltage signal is acquired by data acquisition card in NI-6008, and calculate the displacement through the acquisition of voltage signal. The main microwave structure of high-power tuner is simulated on HFSS, the simulation results showed that the designed tuner can match the demand of VSWR and scope of impedance deployment. Finally, the tuner was processed and measured.For the problem that time of traditional calibration method is too long, this thesis proposed a new quickly calibration algorithm, write the algorithm theory and implement the corresponding algorithm. According to the study on transmission line theory and coaxial waveguide theory, amplitude and phase of reflection coefficient is to satisfy certain mathematical formula when the slider changed in the horizontal position. So as long as we measure the amplitude and phase of reflection coefficient when slider in a fixed horizontal displacement and changed the vertical displacement of the slider, and reanalysis the mathematical formulas when they change with the horizontal position of the slider, then the amplitude and phase of reflection coefficient can be obtained in other horizontal position. By analyzing and comparing the error of S parameter between the new calibration algorithm and the real test results, it can be got that this new calibration algorithm error is small and meet engineering needs. Also, a network cascade calibration is proposed for the tuner.