In the paper, a compact broadband 3×3 Nolen matrix with flatten output ports phase differences is presented. By using two types of three-branch quadrature couplers, wideband impedance matching and flatten output ports amplitudes are obtained. Besides, imbalanced output ports phase differences are compensated by inserting two differential phase shifters between the couplers. Design equations for the proposed structure are derived, and influences of the two differential phase shifters on the phase differences of the Nolen matrix are investigated. To verify the effectiveness of the structure, a prototype operating at 5.8 GHz is fabricated and measured. Measurement results agree well with the simulated ones. Fractional bandwidths (FBWs) of 31.21% and 45.17% are obtained for 15-dB return loss and 15-dB isolation. Moreover, under the criterions of amplitude imbalance < 1 dB and phase difference < 5°, the measured FBWs are more than 23.20% and 23.96%, respectively.
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