Circuit Model for Obliquely Arranged Cables used in Conducted Emission Test Simulation and its Evaluation using TDR

In this paper, the authors proposed the circuit model for obliquely arranged cables. The cables were divided into short segments, which were parallel to the horizontal and vertical conductor planes as reference ground, and these segments were connected in series to construct the overall model. The model parameters of each segment were determined via electromagnetic field simulation using quasi-static approximation and data interpolation. To validate the proposed model, an obliquely arranged transmission line was measured using time domain reflectometry (TDR), and the results were compared with the circuit simulation results obtained using the finite difference time domain (FDTD) method. The results showed that the variation in line constants attributed to the oblique arrangement could be determined through TDR measurements. The line constants obtained using the circuit model agreed with the TDR measurement results, which confirmed that the proposed circuit model was appropriate. The frequency-dependent behavior of the circuit model was verified by comparing the measured reflection of the common mode with the calculated results using the circuit model operated in the frequency range of 0.15 MHz–500 MHz. The calculated results were similar to the measured results, confirming the validity of the proposed circuit model.