Using analysis method to calculate the mutual impedance of microstrip antennas

The mutual coupling between microstrip structures should be taken into account in the design of microwave integrated circuits and microwave arrays. Unfortunately, the tedious calculation of Sommerfeld integrals, which occur when electric field integral equations (EFIE) and the moment method (MM) are involved to deal with the mutual coupling, has made the analysis of mutual coupling difficult. In this paper, a new method combining an asymptotic extraction technique and expansion method was presented. Using this method the dimension of the Sommerfeld integrals were lowered, so the aim to improve the calculation efficiency that could be achieved. Finally, the impedance of several microstrip antennas were determined with this method, to demonstrate the efficiency of this method. Numerical results have shown the high efficiency of the method.