Widening Butler matrix bandwidth within the X-band

Electronic scanning of antennas is accomplished using beam forming networks (BFNs). A widely used BFN is the Butler matrix, a circuit type beam former. The conventional Butler matrix consists of hybrids and phase shifters. Since they are constructed with simple transmission lines, they are inherently narrow band structures. A novel design of Butler matrix is presented, which enhances the bandwidth by using broad banding techniques to obtain wider bandwidth performance from the transmission point of view. Problems encountered in designing such networks at high frequencies are addressed.