Higher order asymptotic boundary condition for the finite element modeling of two-dimensional transmission line structures

The general form of the solution to Laplace´s equation is used to derive a higher-order asymptotic boundary condition. The boundary condition is then implemented in the finite element scheme to model two-dimensional transmission line structures operating in the quasi-TEM mode. The boundary condition is generalized and made valid for an arbitrary outer boundary. The operator is applied on a rectangular outer boundary because that is the most conformable outer boundary for the structures considered. The numerical results of two- and six-conductor configurations showed that the higher-order asymptotic boundary condition yielded a significant improvement over the simple asymptotic boundary condition