A Single-Ended to Balanced Two-Section Branch Line Coupler Based on Integrated Substrate Gap Waveguide

A single-ended to balanced two-section (SETB) branch line coupler based on integrated substrate gap waveguide (ISGW) is presented in this paper. Its center frequency is 27GHz. Compared with the traditional branch coupler, the coupler enhances the bandwidth by using twosection branch-line coupler circuit structure. The coupler can not only be used in 5G millimeter wave communication systems, but also can be used to connect single-ended systems and balanced systems directly. The simulation results show that the relative bandwidth of the coupler is 38%, impedance matching, port isolation, and common mode (CM) conversion suppression are also obtained well for it.