A Substrate Integrated Gap Waveguide Based Wideband 3-dB Coupler for 5G Applications

A wideband 3-dB coupler using substrate integrated gap waveguide (SIGW) is proposed based on the principle of the branch-line coupler structure. The SIGW coupler design is comprehensively studied. It is found that SIGW conducting ridge vias play a significant role and have a strong impact on the cavity resonance, passband, and impedance matching. A prototype of the proposed SIGW coupler is fabricated and tested, and the measured agrees well with the simulated. The coupler, better than the reported, has a passband of ~5 GHz from 23.59 to 29 GHz with the isolation above 20 dB, covering the 24.25–27.5-GHz and 27.5–28.5-GHz frequency bands of 5G.