Abstract:Due to the complex electromagnetic environment, Electromagnetic Compatibility(EMC) problems emerge, and the impact of interference on transmission lines can not be ignored. Based on the classical field-line coupling model―Agrawal model, this paper calculates the electromagnetic coupling effect of each field-line parameter of Twisted-Wire Pair(TWP) with Finite-Difference Time-Domain(FDTD), and gives guidance on the field-line configuration to reduce the disturbance. Finally, the influence of each parameter on the electromagnetic coupling effect of the interference source on the twisted pair is summarized: length will affect the frequency selection characteristic at the terminal load; the effect of pitch is small, and the shorter pitch will decrease the coupling; the height significantly affects the electromagnetic coupling, and the higher the height, the greater the coupling is; the incidence angle, azimuth and polarization angle all influence the electromagnetic coupling effect differently, and it can be seen from the tangential component of electric field's slice diagram that the analysis on one corner needs to take into account the influence of the other two corners. The electromagnetic coupling effect of TWP transmission line is closely related to the field line parameters, and each parameter shows different degrees of influence. Through the calculation of the model in this paper and the analysis on the results, an effective configuration of low-disturbed TWP transmission line can be obtained.