Minimising mutual coupling in thick substrate microstrip antenna arrays

A new method based on the reaction concept, is used to access the mutual coupling experienced by two adjacent circular microstrip antennas on a thick substrate. The coupling owing to surface waves is separated out from that due to the direct radiation and the large interference effects exhibited by the former create deep nulls in the overall mutual coupling characteristic; the nulls being dependent on the given choice of substrate geometry and element separation distance. Finally, the application of this coupling minimisation technique to practical arrays having many elements is briefly commented on.