A broadband 4x4 Butler matrix for modern-day antennas

A broadband Butler matrix was designed manufactured and measured, excellent amplitude and phase characteristics were obtained over 1 GHz frequency band centered at 2.5 GHz which makes it very attractive for multi-band multibeam antenna applications. Many aspects of adequate designs of such a network are presented as well as analysis of the influence of components' performance to overall network characteristics. Also detailed analysis of a transmission line crossover, which is a neccesarry element when a fully integrated antenna array is to be designed, is comprehensively investigated and a novel compensation technique of the deteriorative mutual coupling is proposed. Measurements of a 4 x 1 planar antenna array with the use of our Butler matrix are presented.