An asymptotic closed-form representation for the substrate-superstrate Green´s function (microstrip antennas)

In order to overcome the limitations of previous methods (the spectral- and spatial-domain methods) for analyzing problems connected with the grounded double-layer (substrate-superstrate) configuration, the authors propose the use of an asymptotic closed-form representation of the spatial Green´s function. This approach makes the mutual coupling computation extremely efficient and can be used even for relatively small lateral distances between source and observation points (usually down to a few tenths of the free-space wavelength). Numerical results are presented.<>