Extraction of L parameters for closely separated multiconductor transmission lines over a finitely conducting ground

In this paper, a method is presented to extract the per-unit-length inductance matrix L for closely separated multiconductor transmission lines having conductors with any kind of cross sections over a finitely conducting ground in frequency domain. First, the L over a perfect conducting ground is obtained from the per-unit-length capacitance matrix C by using finite element method. Then the effect of the perfect conducting ground is replaced by that of the finitely conducting ground. Thus, the proximity effect, the effects of both noncircular cross section and finitely conducting ground are taken into account. Some transmission properties of the cables on the chassis of a fuel cell bus made of steel frame is analyzed.