A lumped-element directional coupler with arbitrary output amplitude and phase distributions

A directional coupler with arbitrary output amplitude and phase distributions is proposed. Design equations and experimental results are presented and compared with numerical simulations. During the presentation, the use of the coupler as a building block for a Butler matrix will be shown. The proposed coupler achieves a significant size reduction over conventional couplers. It is five times smaller than a classical branchline coupler, and may provide an attractive solution for applications that require size reduction.