Substrate-integrated waveguide (SIW) out-of-phase T-junction

A planar substrate-integrated waveguide (SIW) T-junction, with transmission properties similar to an E-plane waveguide T-junction, is described. It comprises an SIW H-plane T-junction, and phase-inverting and phase-non-inverting sections inserted into the arms of the T-junction. The inverting section comprises a coplanar-waveguide (CPW) vertical interconnect that couples a pair of antipodal back-to-back SIW-to-CPW transitions. This arrangement swaps current from the top and bottom walls of the SIW to achieve phase-inversion. The non-inverting section comprises a pair of back-to-back SIW-to-CPW transitions, and is the same physical length as the inverting section and has a similar transmission apart from the no phase-inversion. The junction can be constructed using a 2-layer planar technology such as a double-sided printed circuit board. Simulations of a junction operating from 4 to 6 GHz demonstrate the feasibility of the approach.