Hybrid SIW-GCPW Narrow-Wall 3 dB Coupler

In this paper, a novel narrow-wall double-slot 3 dB coupler is proposed. Efficient coupling is achieved between a substrate integrated waveguide (SIW) and a ground coplanar waveguide (GCPW). Such hybrid integrated coupler combines the low-loss property of SIW with the flexibility of CPW. The coupling mechanism between TE 10 mode of SIW and TEM mode of GCPW is studied. According to the provided theory, a 3 dB coupler is designed and fabricated operating around 18 GHz and achieves a relative bandwidth of 10%. The measured results are in agreement with the simulated ones.