This letter deals with the optimization of the switchon instants of the radio-frequency (RF) switches used for the synthesis of time-modulated linear arrays. It is shown that these additional degrees of freedom allow one to increase the stability of the pattern instantaneously radiated by the antenna. Representative results, obtained by means of a Particle Swarm Optimization, are reported and discussed. (c) 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.