Analytical solution for mutual coupling in microstrip patch antenna arrays

The far-field radiation pattern expressions for a microstrip patch element with sinusoidal current distribution along its length (L) and constant current distribution along its width (W) are presented, assuming that the width of the patch is very small compared to its length. Analytical expressions for mutual coupling between the patch elements are derived and effect of the elemental spacing on the mutual coupling between the microstrip elements is presented. The far-field radiation pattern of the microstrip antenna array is studied taking these mutual coupling effects into account. In an array where the individual patch elements lie in close proximity to each other, the mutual coupling between the array elements affects the resultant far-field radiation. This paper stresses the importance of taking the mutual coupling effects into account and the findings show substantial variation in the resultant far-field radiation pattern of the array due to mutual coupling effects.