Asymptotic closed‐form representation of the spatial microstrip dyadic green's function

An asymptotic closed‐form representation of the spatial microstrip dyadic Green's function is developed. This representation is very efficient for a numerical evaluation of the field when the source and the observation points are laterally rather than vertically separated with respect to the interface plane. Numerical examples are presented that indicate that the representations obtained are very efficient even for relatively small lateral separation of the source and field points. This work is especially useful in the moment‐method analysis of microstrip antenna arrays where the mutual coupling effects are important.