A Hybrid SIW and GCPW Guided-Wave Structure Coupler

Since substrate integrated waveguide (SIW) is not directly compatible with active circuits, additional transitions to planar transmission lines are indispensable. In this letter, a novel hybrid SIW-CPW structure coupler applying an antenna feeding network is presented. SIW is used as the radiating portion while coplanar waveguide (CPW) is the input matching portion that is connected directly to the active circuits. Without any transition structure, the whole system can be more compact. In addition, this hybrid coupler has a relative bandwidth of over 30% with the broadband amplitude and phase balance characteristic of CPW.