Scattering parameters (S-parameters) and passive intermodulation (PIM) characterize the signal integrity for small signal excitation and nonlinearity for high-power excitation. In this letter, a model that relates the S-parameters and PIM is theoretically proposed and experimentally verified. A simplified PIM model is presented to investigate the effect of impedance mismatch between two nonlinear points on the reflected intermodulation (IM) powers. Considering the impedance discontinuity induced by line bending, the impact of different bending angles on transmission phase and signal reflection is simulated. Through the combination of S-parameter modeling and passive nonlinear transfer functions, an equivalent circuit is developed to simulate the IM3 powers resulting from connector–microstrip assemblies with different line bending angles. In addition, a series of PIM tests are conducted with customized samples. Experimental results are consistent with the predictions, showing the effect of the scattering characteristics on the PIM.

中文翻译：

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线路弯曲引起的阻抗不连续性对连接器-微带组件中无源互调的影响

散射参数（S 参数）和无源互调 (PIM) 表征小信号激励的信号完整性和高功率激励的非线性。在这封信中，理论上提出了一个将 S 参数和 PIM 关联起来的模型，并经过实验验证。提出了一个简化的 PIM 模型来研究两个非线性点之间的阻抗失配对反射互调 (IM) 功率的影响。考虑线路弯曲引起的阻抗不连续性，模拟了不同弯曲角度对传输相位和信号反射的影响。通过结合 S 参数建模和无源非线性传递函数，开发了一个等效电路来模拟不同线路弯曲角度的连接器-微带组件产生的 IM3 功率。此外，还使用定制样品进行了一系列 PIM 测试。实验结果与预测一致，表明了散射特性对 PIM 的影响。