Influence of finite ground planes on the transmission line current distribution

The knowledge of the current distribution on the ground plane of a printed circuit board (PCB) is important to overcome many electromagnetic compatibility (EMC) problems. In this paper a method of moments (MoM) algorithm is used to evaluate the surface current distribution on the ground (GND) plane. In order to consider the effects of GND-planes on the signal behaviour on transmission lines, infinite planes are often assumed to reduce the calculation time. A comparison of the currents using finite and infinite ground planes shows a significant modification of the coupling to transmission lines placed in the layer above.