Mutual coupling effects in microstrip patch phased array antenna

Low orbit global satellite communication systems require low cost user terminals. A low cost microstrip patch phased array antenna is the most possible choice. For a wide frequency band and wide scan angle microstrip patch phased array antenna, the use of a thick patch substrate results in an increased excitation of surface waves. The mutual coupling effects caused by these surface waves have to be taken into account in the design. This is especially true for the design of microstrip patch arrays for future satellite communication systems, which will consist of several hundreds of microstrip patch elements. This article introduces a simple calculation procedure of the active reactive coefficients and radiation patterns of a finite size element microstrip patch phased array. The active impedance is calculated by matrix summation of isolated element impedance and mutual coupling between any two elements. Once the active element impedance is calculated, the radiation pattern can be calculated using the excitation voltage of each element. Some calculated results are shown.