REDUCED SIZE BULTER MATRIX FOR SMART ANTENNA SYSTEM

The present invention provides for a realization of a Butler Matrix (10) microwave network of reduced size that includes a plurality of input and output ports, utilizing a plurality of reduced size branch-line couplers operating at 1.8 GHz. The reduced size of the branch-line coupler (20) renders the present invention suitable for application requirements such as mobile device applications. The branch-line coupler (20) has been used as the fundamental component in constructing the planar Butler Matrix microwave network (10). A Butler Matrix microwave network (10) consists of branch- line couplers (20), crossovers (40) and phase shifters (42, 44). The reduction in size of the branch-line couplers (20) utilized in the reduced size Butler Matrix (10) of the present invention is achieved by using two step stub impedance, whereby the area of the branch line coupler (20) is reduced by up to 66% from the normal size.