FDTD analysis on the current and electric field distribution in a PCB stripline structure

An FDTD analysis is reported on changes in distributions of the stripline current, image current and electric field in a PCB stripline structure of stripline-dielectric-ground plane as the dielectric thickness and stripline width are varied and these distributions are described graphically. As the ratio of the stripline width w to the dielectric thickness h, w/h, went to greater than 1, the stripline current was distributed on the bottom side of the stripline, the image current was concentrated just under its corresponding stripline, and most of the emitted field produced by the stripline was confined within the dielectric. As the ratio went to less than 1, the stripline current started being distributed on all the outer surface of the stripline, the image current was more spread in its width, and more emitted field came out of the dielectric. Variation of w/h from 0.1 to 2 caused only a little change in the stripline current and electric field intensity inside the dielectric, but the field is much reduced outside both in intensity and spatially, which means that decrease in the dielectric thickness could raise the PCB circuit density.