Modal expansion absorbing boundary conditions for two-dimensional electromagnetic scattering

A novel absorbing boundary condition is developed using modal expansion basis functions. The main advantage of this procedure is that it is more accurate than the boundary condition proposed by A. Bayliss and E. Turkel (1982) when the boundary is very close to the scatterer. The modal expansion absorbing boundary condition is accurate with both circular and noncircular boundaries, and preserves the symmetry of the global matrices when combined with the finite-element method (FEM). Numerical tests show that for typical applications, the accuracy of the near field is within 4% of analytical values