© 2019 IEEE.We present design and optimization of nanoarrays, which consist of metallic nanoparticles that possess plasmonic properties. Optimal two-dimensional arrangements of nanoparticles are found by using an optimization environment involving genetic algorithms and a three-dimensional full-wave solver based on the multilevel fast multipole algorithm. The nanoarrays are designed to provide maximum radiation at desired directions when they are excited via isotopic sources. The designed structures and their radiation characteristics are extensively investigated by considering various parameters, such as grid size, nanoparticle shape, distance between nanoparticles, and material. The results demonstrate the favorable radiation characteristics of the designs, as well as the capabilities of the optimization environment to design compact nanoarrays for beam-steering applications.