Correction factors for field singularity at 45° corners in the finite-difference analysis of microstrip circuits

In microstrip circuits, the field concentrates at the edges and corners of a thin strip conductor. This yields rapid variation of field strength with its position in their proximity, which might cause a significant error in the finite-difference approximation of the field analysis. The accuracy may be improved by using finer discretization. However, refining the grid in three-dimensional space will soon require huge computational resources. It would be beneficial to improve the accuracy without largely increasing the analysis cost. To this end, a modification of the finite-difference formulation for the local field singularity was proposed previously. This paper presents the correction factors for 45° corners of thin metal plate used for the modification and examines the accuracy improvement in the analysis of microstrip structure.