Analysis of external electromagnetic interference noise induced to twisted wire pair Network over ground using improved Baum-Liu-Tesche(BLT) method

Abstract

ElectroMagnetic Interference(EMI) noises incident from outside the system, such as aircraft and automobiles, are directly coupled to the external cable of the system or to the internal cable of the system through antennas and openings, thereby reducing the performance of the mounted equipment. A Twisted Wire Pair(TWP) wire is often used in systems to minimize these external EMI noises induced into cables of the equipment. Although numerical analysis methods based on the Maxwell equation such as FDTD and MoM analyze exactly the TWP, they are not suitable for use as the methods for the cable analysis because they require a lot of mesh to draw the TWP in three dimensions. Baum-Liu-Tesche(BLT) method based on electromagnetic topology environment, which is most commonly applied for the electromagnetic coupling analysis of cable networks, has faster calculation time than that of the numerical analysis methods because the transmission line theory is applied. However, because the TWP has nonuniform shapes repeatedly, If the BLT method is used to calculate the TWP, the dimensions of the propagation tube and scattering supermatrices rapidly increase and calculation time become longer as well. In this paper, an improved BLT method using chain or chain scattering matrices was proposed to overcome the disadvantages the conventional BLT method and the response of the external EMI induced to the cross-shaped network over ground consisting of TWPs was analyzed. we compared results of the proposed method with those of the MoM and experiment and verified to show similar results each other.