The effect of mutual coupling on the input impedance of microstrip arrays

Mutual coupling between microstrip patch antennas is formulated using the cavity model and the reaction concept. The method is applied to obtain the mutual admittance of two identical circular patches. Expression for the mutual admittance is used to determine active input impedances of elements in a 19-element hexagonal phased array antenna. Numerical results reveal the importance of mutual coupling effects in the performance of a phased array antenna.