This paper presents a new architecture to minimize the size of conventional phased array antenna. The proposed size reduction of the phased array is achieved by designing the whole system to support dual-band operations. To verify the design concept, a novel dual-band phased array feeding network is designed based on a dual-band 4×4 Butler matrix. By integrating the proposed 4×4 dual-band feeding network with antennas, a total of eight radiation beams can be generated, indicating a size reduction of about 50%. The designed phased array feeding network is operating at 5 and 8GHz. Simulation results show the eight radiation beams as predicted by the design theory, which further validates our design concept.