Approximate Green´s Function for a Finite and Electrically Thick Dielectric Slab

An approximate two-dimensional Green´s function for an electrically thick and large dielectric slab is presented. In doing so, we first obtain the interior Green´s function which solves the case when the source and field points are inside the dielectric slab. For the cases when the source and/or field points are outside the slab, the Green´s function is obtained using the interior Green´s function and the surface equivalence principle. According to the surface equivalence principle, having the interior Green´s function is adequate to find the solution for the arbitrary source and field point positions. The solutions for all possible cases are obtained numerically and are validated by comparing to the results generated by the surface integral equation/method of moments.