A compact Switched Parasitic Array (SPA) suitable for 2.4 GHz ISM applications is presented in this paper, which is designed using a proposed method based on self and mutual impedance measurements and optimized by a custom-designed Genetic Algorithm (GA). The proposed technique is applicable for Electronically Steerable Passive Array Radiator (ESPAR) as well as SPA antenna development. It is especially suited for cases where commercial elements are used as building blocks of the antenna array, since in such cases conventional numerical-based techniques used in the literature are not applicable.