Abstract
Electromagnetic disturbances in vehicle-mounted FM radios are mainly caused by conducted noise currents flowing through wiring-harnesses from printed circuit boards (PCBs) with the slits of ground patterns. To suppress these kinds of noise currents from PCBs, we previously performed the FDTD simulation and measurement using plural simple two-layer PCB models in which the ground patterns were divided into two parts with different widths, and revealed that the both results agreed well with the fact that the cross-talk cannot always be reduced by widening the width of divided ground patters but had the smallest values (dipping point) at specific space between the divided ground patterns. In order to clarify the above result, we calculated cross-talks using a formula developed from a simplified equivalent circuit model consisting of inductances, which were derived from their geometrical mean distance for the traces and ground patterns, and found that the calculation results also had the dipping point however the specific space and cross-talk values were different from the simulations and measurements. In the present study, to improve the calculation accuracy, we considered the non-uniformity of current distribution on the ground patterns instead the uniform current distribution, and obtained the evaluated cross-talk results which agreed better with simulations and measurements.
