Beamforming networks using reduced size and Cascaded Butler Matrices

This paper presents the design and realization of reduced size branch-line coupler operating at 2.45GHz. Wireless communication has created a continuing demand for increased bandwidth and better quality of services. Smart antenna systems are one of the ways to accommodate this demand which can provide numerous benefits to service provider and the customer. Nowadays people tend to choose the compact and smaller size for wireless devices. Therefore, size reduction of branch-line coupler using eight two-step stubs has been proposed in this work, where the area of branch-line coupler has been reduced up to 50% from the normal size. The practical application of this reduced size branch-line coupler has been implemented on a 4×4 Butler Matrix which consist of branch-line coupler, crossover and phase shifter. Results from simulation are obtained by using Advanced Design System (ADS) in term of S-Parameter analysis and the phase difference between ports. The Butler matrix has been fabricated on Flame Resistance Board (FR4 Board). The measured results show satisfactory performance and good agreement with the simulated results.