Coupling in some edge-coupled microshield transmission lines

Using the finite-difference time-domain (FD-TD) method in the Cartesian coordinate system, the coupling effects in some (a)symmetrical edge-coupled V-shape and trapezoidal microshield transmission lines (MTLs) are studied. The hybrid effects of different geometrical parameters of the MTLs and the permittivity of the filling materials on the coupling coefficient are examined and compared. It is shown that the edge-coupled V-shape geometry is effective in reducing coupling over a wide frequency range.