Design of broadband planar magic-T using 3-dB branch-line coupler and phase shifter

In this paper, a broadband planar magic-T using 3-dB branch-line coupler and phase shifter is presented. The magic-T consisted of a planar branch-line coupler and a planar phase shifter respectively. Compared with the conventional magic-T, which using slot-line transition or waveguide magic-T. The proposed structure can be easily fabricated and integrated in system. Simulation results show our magic-T exhibits excellent performance at broad bandwidth. The relative bandwidth is 40% with the VSWR is less than 1.4, and the amplitude imbalance is less than ±0.5dB, and the phase ripple is better than ±3°, as well as the isolation is greater than 18dB.