This paper presents a four-element linear arraycomposed of E-shaped microstrip antennas designed to switched-beam application in ISM band. Particle Swarm Optimization(PSO) algorithm is applied to optimize four different sets ofamplitude and progressive phase shift to achieve four distinctradiation patterns controlling the major lobe direction andsidelobe level. For this application, two restrictive approachesare presented for the implementation of PSO algorithm in orderto improve the algorithm convergence to feasible solutions.