In this chapter, the smart antenna concept is introduced. The smart antenna is an emerging technology that can be used to tackle the capacity, quality, and coverage problems faced by wireless communication under heavy traffic. It finds its applications in many fields such as military, commercial, and medical. The chapter is organized as follows. First, the problems faced in wireless communication are introduced and the need for the smart antennas systems to solve these bottlenecks is explained. Next, the existing algorithms for smart antennas are explained. A direct data domain approach based on a single snapshot of data, in which there is no need to form a covariance matrix, is explained in detail. Next, the eigenvalue method, forward method, backward method, and forward-backward method are introduced, and simulation results and conclusions are provided.