Broadband 3 x 3 butler matrix

Abstract

In this paper, a novel design of a broadband 3 x 3 Butler matrix is proposed. It is composed of three single-section coupled-line directional couplers and two Schiffman phase shifters and operates in the frequency range 2.5 GHz - 3.5 GHz. The fabricated 3 x 3 Butler matrix features very good frequency response in terms of transmission imbalance, isolation and impedance match.