Waveguide with edge grounding

Abstract

A waveguide structure and associated method for forming the waveguide structure is disclosed. The waveguide structure is formed from at least two dielectric layers having opposing, substantially planar faces and an intermediate signal path layer positioned between the faces. A conductive layer is formed on each of the opposing, substantially planar faces to form outer ground planes. At least one controlled impedance signal track is formed at the intermediate signal path layer. A plurality of conductive vias extend through the dielectric layers and interconnect the ground planes. The vias form a 'sea' of vias, which provide enhanced waveguide mode rejection. A plurality of grounding lines interconnect the vias at the intermediate signal path layer. A conductive via is connected to all adjacent conductive vias outside the controlled impedance signal track to form an inner grounding line grid that is coplanar with the controlled impedance signal track for waveguide mode rejection. The waveguide structure can be formed from two dielectric layers laminated together, and the grounding lines and controlled impedance signal track can be formed by using standard photolithography methods consisting of substrate etching and/or additive processes.