Closed-form expressions for the numerical dispersion and reflection in FEM simulations involving biaxial materials

Closed-form expressions for the numerical errors caused by finite-element discretization of problems involving materials of biaxial permittivity and permeability tensors are developed. In particular, we derive expressions for the numerical dispersion and reflection in both first-order node and edge basis function finite-element formulations in an equilateral triangular mesh. Results using these closed-form expressions are compared to practical numerical simulations. The application of these expressions to the analysis of the performance of the perfectly matched layer boundary is suggested.