Optimal Design of a Highly Compact Low-Cost and Strongly Coupled 4 Element Array for WLAN

A 4 element array of microstrip E shaped patches is designed for use in wireless local area network (WLAN) applications. The operating frequency range is from 3.4 to 3.8 GHz and the gain of the array is more than 13 dB. The main beam direction is normal to the ground plane. Considering the specifications given, the focus is on the reduction of occupied space. This implies the use of an integrated feeding technique in combination with highly coupled array elements. Although the concept was published before, no optimizers were used and the previous design did not meet the 10 dB matching criterion. It is clearly proven that, due to its complexity, this innovating topology can be fully taken advantage of only by designing it using efficient evolutionary optimizers. Both a particle swarm optimization (PSO) and a genetic algorithm (GA) technique are used. During the optimization process, the fitness is evaluated by using a full wave solver based on the method of moments (MOM). It is shown that for these types of structures, a single step optimization procedure is preferred, and PSO outperforms GA. CST EM Studio is used for validation purposes before manufacturing. A prototype array is fabricated and measured.