A Compact Four-Way Power Combiner

A compact 8-port waveguide network is proposed in this letter. It is constructed by cascading two compact coaxial magic-Ts and one coplanar coaxial waveguide magic-T in series. Based on the 8-port waveguide network, a four-way power combiner is realized with three matching ports connected to loads. Measurements show that from 7.8 to 10.3 GHz, the return loss is greater than 18 dB, the isolation is greater than 21 dB, the insertion loss is less than 0.4 dB, and the amplitude and phase imbalance are less than 0.3 dB and 3°, respectively. Its cross section areas are approximately 1.1λ × 1.1λ for the central frequency of 9 GHz. The measurements agree well with the simulations.