Using polygonal defect in ground structure to reduce mutual coupling in microstrip array antenna

The surface wave propagation is a significant problem in designing microstrip array antennas that causes the mutual coupling between array elements. There are several methods to suppress this effect and decrease the propagation of surface waves,such as using defected ground structures (DGS). Determining the shape of DGS is the main difficulty when using these structures. In this paper,a new method is proposed to be used in designing array antennas in which the slot shape of DGS in the ground plane of the antenna is assumed to be a polygon, and its shape is obtained by using the enhanced genetic algorithm (GA) and ant colony optimization (ACO). In this case, an array antenna with two elements is designed to work in 9.5GHz and the gain, return loss and mutual coupling of this antenna is optimized. Finally, the design procedure is verified by simulation and measurement.