A novel method based on the memetic algorithm for uplink Spatial Division Multiple Access (SDMA) optimization technique of smart antennas via the phase-amplitude perturbation method is proposed. The array factor formula is deduced to search the optimal weighting vector of the array factor of a smart antenna. In a smart antenna system, one user's signal must be considered as other users' interfering signal. An optimal radiation pattern of a smart antenna can not only adjustably suppress interferers by placing nulls at the directions of the interfering sources but also provide a maximum main lobe in the direction of the desired signals at the same time so that SDMA can be come true. In order to achieve this goal, a new convergent method referred as the two-way convergent method for memetic algorithms is proposed.