一种快速测试线缆终端共模阻抗的方法

航空电子设备之间的互联线缆是电磁干扰耦合的重要路径。对线缆耦合进行建模分析时，线缆终端共模阻抗是至关重要的输入参数。而航电系统线缆数量较多，提高线缆终端共模阻抗的测试效率，有利于快速建立线缆耦合模型。为此，提出了一种快速测试线缆终端共模阻抗的方法。首先，根据多导体传输线理论证明，在分析共模电流时可以将多芯线缆等效为一根单导体。进而，将线缆束等效为多导体传输线，并采用矢量网络分析仪和电流探头测量各条线缆2个任选位置处的电压反射系数。然后，基于所建立的多导体传输线模型，构造以终端阻抗为未知数的方程组。最后，采用数值迭代算法求解该方程组，得到各条线缆的终端共模阻抗。与现有方法相比，所提方法提高了测试效率和测试精度。

A method for quick measurement of terminal common-mode impedance of cables

The cables connecting avionics equipment are important coupling path for electromagnetic interference. When modeling a cable, the terminal common-mode impedance of the cable is a crucial input parameter. Because the quantity of cables in avionics system is very large, it is beneficial for quickly modeling cables' coupling through improving the test efficiency of cable terminal common-mode impedance. Therefore, a method to quickly test the terminal common-mode impedances of cables is proposed. First, according to the theory of multi-conductor transmission line, the multi-core cable can be equivalent to a single conductor when the common-mode current is analyzed. In addition, a cable bundle can be equivalent to a multi-conductor transmission line, and a vector network analyzer and a current probe can be used to measure the voltage reflection coefficients at two optional positions of each cable. Then, based on the established model of multi-conductor transmission line, the terminal impedance equations are constructed. Finally, the numerical iterative algorithm is used to solve the equations, and the terminal common-mode impedance of each cable is extracted. Compared with the existing methods, the testing efficiency and accuracy are improved.