Accurate Evaluation of Field Interactions Between Cable Harness and Vehicle Body by a Multiple Scattering Method

Interactions between cable harness and vehicle body can be calculated using the full-wave method-of-moments (MoM) formulation. Although the full-wave MoM formulation can help us to calculate these interactions with great accuracy, it can be fairly time consuming when dealing with complex wire structures. On the other hand, the conventional multiconductor transmission-line theory can be used to obtain a simple model of the interactions, but only the effect of the transmission-line (TL)-mode current can be accounted for in this method. Starting with the complete electrical field integral equations, the current on a two-conductor thin wire structure due to incident field illumination can be decomposed into TL and antenna modes. Both modes can be solved using a SPICE solver in the form of Telegrapher's equations. A proposed multiple scattering (MS) method based on a hybrid of TL and surface MoM can then be used to calculate interactions between thin wire structures, such as cable harness, and conductive surfaces, such as vehicle body. A test case shows that wire current computation using the proposed MS method takes less time but reaches the same accuracy compared to the full-wave MoM.

I. Introduction

The modeling of cable harness along with vehicle body is important for vehicle electromagnetic interference (EMI) design since vehicle harness can act both as a source of radiation and the victim of undesired coupling. The radiation from antenna-mode current on the cable harness can illuminate the vehicle body and further radiate into outer environment as electromagnetic (EM) pollution. Additionally, external fields coupled to the cable harness via the vehicle body can introduce EMI problems that are prevented through constrains on packaging, harness routing, and shielding requirements to meet strict electromagnetic compatibility (EMC)/EMI requirements. Detecting these issues in the early stages of vehicle design through vehicle-harness cosimulation can reduce design cost and help us to achieve compliance with EMC/EMI requirements without a need for a redesign. Over decades, statistical analysis, full-wave simulation method, as well as several hybrid methods have been developed to model the cable harness.