Rigorous full-wave space-domain solution for dispersive microstrip lines

The eigenmode problem for the open microstrip line is analyzed in the space domain starting from the calculation of a dyadic Green´s function in the spectral domain. The transverse and the longitudinal current are discretized using the method of moments. A point-matching technique is used to impose the boundary condition, i.e., zero tangential electric field, on the strip. The edge conditions at the end points of the strip are explicitly incorporated and special care is taken to accurately retain the static behavior of the field on and near the strip. Special attention is given to the variation of the current distribution as a function of frequency