Study Of Analysis Method Of Nonlinear Parameters In Microwave High Power System

As the high-power multiple-channel communication systems are more widely applied in the field of modern communications, nonlinearity produced by passive components(filter, power divider, coupler, connector, transmission line) has seriously affected the communication system channel capacity and quality of communication. PIM(abbreviation of Passive Inter-Modulation) is the new frequency component generated by two or more frequencies mixed in passive components. This paper is based on the PIM generated by the passive components in a high-power travelling-wave tube(TWT) test system which can affect the test accuracy of the system. Therefore, the analysis and research of the PIM can achieve the error analysis of the high-power test system.Firstly, this paper introduces the developments of the study of the PIM at home and abroad, analyses the characteristics and mechanism of the PIM and several measures to reduce the PIM, and compares some approaches of passive nonlinear analysis. This paper analyzes the mechanism of the PIM of the RF connector, builds the Point-Source Model of PIM in the RF connector and has theoretical analysis, and develops a simulation software. This paper also analyzes the effect of the harmonic components of the signal source and the nonlinearity of pre-driver amplifier on the linearity of TWT.Secondly, comparing the passive nonlinear test methods and combining the research object and the experimental conditions, this paper gives the comparison test method for nonlinearity of the RF connector. A high-power, low PIM, narrow and band pass is designed. The center frequency is 1.85 GHz and the bandwidth is 30 MHz. This filter is tested and the test result shows that the designed filter reached the expected target. Using the filter, PA, power combiner and directional coupler and so on, a verification test system is set up.Finally, According to the theoretically analyzing and verifying the testing results. For the high power TWT nonlinear test system, the error analysis of this system’s nonlinearity is analyzed. The simulation software of the nonlinear parametric test error is written, and the testing error of nonlinear parameters of this system is obtained.