Multilayered Discrete Green's Functions Based on Mixed-Potential Finite-Difference Formulation

An approach to calculating discrete Green's functions (DGFs) in multilayered media is proposed based on the finite-difference scheme of time-domain mixed-potential equations. The calculated DGFs have very high accuracy in comparison to the direct FDTD solution. Furthermore, the steady-state values of the DGFs are properly estimated in terms of the scalar potential, ensuring stability out of the truncating window. These DGFs are applicable to the analysis of antennas with multilayered planar structures. In such analysis, the proposed method has the advantage of the method of moments in that the computations are performed only on the antenna, regardless of the white space around it. Moreover, the broadband frequency characteristic of the antenna is achieved with a single simulation run, such as in the FDTD method. The theoretical results have been verified by the experimental results on a wideband coplanar waveguide (CPW)-fed monopole antenna.