A Wideband 3 x 3 Nolen Matrix With Flat Phase Differences

In general, the Nolen matrix exhibits narrowband characteristics, which restricts its application in beamforming networks. In this paper, a wideband 3 x 3 Nolen matrix with flat phase progressions is proposed based on the modified two-section branch-line quadrature couplers and broadband phase shifters using λ/8 open and shorted stubs. For validation, a 3 x 3 Nolen matrix centered at 3.5GHz is designed, fabricated and measured. Simulated and measured results are in good agreement. Overall available bandwidths of the input ports 1–3 are 12.96%, 15.34% and 15.56% respectively. This wideband Nolen matrix exhibits flat phase differences and is well suited for wideband LTE applications.