Finite-difference formulation accounting for field singularities

Correction factors are introduced into the finite-difference formulas which diminish the discretization error for the grid cells adjacent to field singularities. The correction factors are calculated by an iterative numerical method that can be applied to all types of rectangular edges and corners between ideal conductors and different dielectrics. Examples using a code of finite-difference method in the frequency domain show the resulting improvements in terms of accuracy, CPU time, and memory for typical monolithic-microwave-integrated-circuit three-dimensional structures.