Excitation of a triangular lattice EBG waveguide by an incident plane wave

A triangular lattice of holes with partial bandgap is used to design an EBG waveguide for TM modes (magnetic field parallel to the substrate surface and perpendicular to the holes) for operation in the millimeter wave range. The fundamental guided mode of the designed waveguide has a quasi-TEM nature. This waveguide is designed to serve as a building block of a spatial power combiner and it is excited with an incident plane wave. A square lattice of metallic vias was added at the input and output faces of the EBG waveguide to prevent the incident plane wave from penetrating into the triangular lattice of holes and enhance the coupling between the guided mode inside the waveguide and plane wave excitation. The mode matching between the two different EBG waveguides with triangle and rectangle lattices has been investigated. The modal structures of the EBG waveguides were exploited to optimize the structure.