Impact by an orthogonal metal grid upon differential- and common-mode characteristics of coupled lines in PCB technology structures

This paper deals with a rigorous study of the impact by perpendicular metal grids on the characteristics of microstrip and coplanar coupled transmission lines. An electromagnetic analysis shows the variations of the propagation parameters in common and differential modes for each type of lines, in the presence of a metal grid. As transmission zeroes are liable to occur at certain frequencies, in particular in the common mode, we investigated the part played by the most influential grid parameters on these disturbances.