Wideband 3-dB Coupler Based on Substrate Integrated Gap Waveguide

This paper proposed a wideband 3dB coupler based on substrate integrated gap waveguide. The proposed coupler takes the branch-line coupler as the prototype and the simulations have done. According to the simulation results, the proposed coupler achieved the equal power division and the isolation are all above 20dB from 23.59GHz to 29GHz. Moreover, the phases between through port and coupled port differ 90 deg and the losses for both the through port and isolated port are about 1dB. In addition, the comparison of the couplers with different tilt angle coupling lines has been done. And with the simulation results, when the tilt angle equals 0, the bandwidth of isolation above 20dB is about 3 times of the tilt angles equaling λ/4,4λ/25 and λ/6.