Treatment of field singularities in the finite-difference approximation

Due to the discretization of space, the finite-difference method cannot exactly resolve singularities of the electric and magnetic fields at metallic edges. A simple method which reduces the corresponding error without increasing the numerical efforts is presented. The novel edge formulation is tested by calculating the line parameters and the field pattern of a homogeneous MMIC (monolithic microwave integrated circuit) coplanar waveguide. This improved formulation, developed by incorporating a correction factor depending on the field singularity at the edge, reduces the errors by a factor of about one half.<>