In this paper, an innovative optimal radiation pattern of an adaptive linear array is derived by phase-only perturbations using a Particle Swarm Optimization (PSO) algorithm. An antenna array is often made as an adaptive antenna. An optimal radiation pattern design for an adaptive antenna system is not only to suppress interference by placing a null in the direction of the interfering source but also to derive the maximum power pattern in the direction of the desired signal. The Signal Interference Ratio (SIR) can be maximized. The PSO algorithm is a new methodology in this study area, which can handle adaptive radiation pattern of antenna array. In this paper, an optimal radiation pattern of linear array is derived by phase-only perturbations using a PSO algorithm. PSO algorithms will be stated and computed for this problem. Then, the optimal solution can be derived, and simulation results are also presented in this paper.