The expansion wave concept. II. A new way to model mutual coupling in microstrip arrays

For pt.I see ibid., vol.46, no.3, p.397-406 (1998). A new expansion scheme is introduced to solve the integral equations describing the mutual coupling in microstrip arrays. The scheme is based on the fact that at larger distances the Green's functions in the stratified dielectric medium of the antenna structure can be approximated using analytical expressions. This allows one to describe the waves propagating between the elements thus causing mutual coupling with a small number of parameters. Since only these parameters have to be determined, the resulting number of unknowns is much smaller than with conventional rigorous techniques. The accuracy of the scheme is illustrated by a comparison of measured and calculated data for both a two-element and a linear eight-element microstrip array antenna.