On the design of a single-layer wideband Butler matrix for switched-beam UMTS system applications [Wireless Corner]

A Butler matrix (BM) for UMTS applications is presented. The Butler matrix was fabricated by conventional photolithography on a single laminate. The design is compact and complies with the required bandwidth. The design is based on the use of an elliptical coupler with certain geometrical characteristics, and a Lange coupler as a crossover. Furthermore, a design-scaling procedure that produces an N times N Butler matrix by using two (N/2)times(N/2) Butler matrices is given. The presented performance extrapolations clarify the potential and scalability of our approach