This letter presents a new design of a nonuniform antenna array with low sidelobes for fifth-generation (5G) applications. The proposed design consists of 16 square patch antennas with a corporate beamforming network.The patch antennas are in nonuniform positions within the array aperture, and the corporate beamforming network is composed of nonsymmetric curved microstrip lines to connect the antenna elements. The antenna array is configured to be working from 25.08 to 25.44 GHz. The design process was formulated as a particle swarm optimization to find out the optimum antenna positions for a sidelobe level reduction.Simulated and measurement results reveal the array performance with a sidelobe level reduction of −7.57 dBi compared with a uniform antenna array. The optimized array generates a directivity of 12.03 dBi.