无源器件无源互调干扰行为建模

无源互调干扰会影响多载波通信卫星的正常工作，是目前卫星通信系统必须考虑的问题之一。由于无源互调干扰问题具有一定的复杂性，无法直接分析无源互调分量，因此需要建立相应的模型进行研究。针对无源互调干扰的频率分布特点，采用双指数函数模型和Volterrra级数模型拟合无源互调干扰，推导并建立了QPSK调制信号的无源互调干扰时序模型。基于MATLAB的仿真结果表明，无源互调干扰分量的理论值频点处都出现了相应峰值，且其幅度值与输入信号中心频率处的幅度值的比例符合理论分析。

Behavior models of passive intermodulation interference in passive devices

Passive intermodulation often affects the normal operation of multi carrier communication satellites. Because of the complexity of passive intermodulation interference, it is impossible to analyze the passive intermodulation component directly. Therefore, it is necessary to establish models. According to the frequency distribution characteristics of passive intermodulation interference, double exponential function model and Volterrra series model were adopted to fit passive intermodulation interference, and the time series model of passive intermodulation interference of QPSK signals was established. By performing MATLAB simulation, the results show that the peak values appear at the theoretical frequency points. The ratio of the amplitude value at the center frequency of the input signals to the amplitude value at the passive intermodulation frequency components accords with the theoretical analysis.