Efficient calculation of the 2D Green´s function of a truncated grounded dielectric slab

A new efficient method is proposed to derive a series expansion for the 2D Green´s function of a truncated grounded dielectric substrate. We use 2 metal-backed PMLs to turn the original open configuration into a closed one. The resulting structure is then regarded as a waveguide and the resulting-analytically known-discrete set of eigenmodes is then used to expand the Green´s function. The method turns out to be accurate and efficient for distances larger than 0.1/spl lambda/ away from the source and the junction.