In this thesis, we study the array theory and the array synthesis methods to design a sector antenna composed of a broadside collinear array and a corner reflector that is suitable for base stations. The antenna produces a sector beam in the horizontal plane to reduce the co-channel interference. In the elevation plane the antenna produces a narrower beam in order to achieve a higher gain. A uniform array is known to produce a high side lobe level which will cause serious interference. Therefore, Dolph-Tchebyscheff linear array method and Taylor line source method are utilized for the antenna design. We also design the structure of corner reflector which is combined with an array to form the sector antenna. We also study the switched-beam system, design and fabricate a 4¡Ñ1 microstrip patch antenna array to simulate the operation of the system and measure its performance.