Improvement of the absorbing boundary conditions for triangle-hexagonal dual cell grids in the time domain method is described in this paper. The magnetic field components, which are evaluated by the electric fields at the circumcenters of the triangle cells, are conformed to Berenger's perfectly matched layer absorbing boundary conditions. The electric field is linearly interpolated by the fields at the vertices. The lower reflection coefficients in the frequency range for the equilateral and non-equilateral triangle cells are demonstrated.

We have proposed an algorithm to apply perfectly matched layer (PML) absorbing boundary condition to the noncubic cell time-domain method. The extended method has a merit of flexibility in truncating the computational domain by the use of a curvilinear PML. In this paper we apply a circular PML for computing the scattered fields of a dielectric cylinder or cylindrical shell of arbitrary cross section shape. Numerical results are presented to demonstrate the accuracy of this method.