Design of a Terahertz E-plane Waveguide Branch Coupler with Central Slits

We present an E-plane waveguide coupler that can be used in the terahertz frequency band. Several slits are designed in the center of E-plane waveguide. These structures reduce the difficulty of metal processing of the E-plane coupler because of their smaller aspect ratio of branches. The simulation results of the proposed coupler are better than those of the traditional branch coupler. At 206~231 GHz, the amplitude imbalance between the through and the coupling ports of the coupler is less than 0.2dB, the phase imbalance is 90±0.5 degrees, the return loss and the isolation between output ports are better than 25 dB.