A 24-GHz phased array for indoor smart radar is proposed in this paper. This array consists of 6 horizontally placed antenna elements. Each antenna element is a vertically placed 5-element series-fed microstrip patch array. The beam of the phased array can be continuously steered on the H-plane to different directions through a novel vector control array. Each element of the vector control array can adjust the phase and amplitude of the corresponding element of the horizontally placed linear array. The whole phased array system is fabricated on a single printed circuit board (PCB). PIN diodes are used to realize beam steering by modulating the decomposed received signal. In order to compensate for the loss of the vector control array and reduce the noise figure, six low noise amplifiers (LNAs) are also used in the array. This proposed phased array system features a lower cost than conventional solutions based on phase shifters. The principle of the proposed vector control array is discussed, and simulation shows this system has the ability to continuously steer the beam on the H-plane.