US Patent 10418680 Multilayer coupler having mode-compensating bend

A multilayer coupler may include electromagnetically coupled planar first and second signal conductors that are separated by a gap, extend adjacent each other along a ground plane, and change orientation in a bend. A plate may be positioned along the bend between the ground plane and the signal conductors. The ground plane may have an opening extending along the bend and the plate. A multilayer coupler may include two coupled signal conductors formed in a loop having a four-wire section in which different sections of the two signal conductors overlap in a four-wire section. In a transition region in which the coupler transitions from the four-wire section to a two-wire section, an isolating ground plane may separate the two two-wire sections extending from the four-wire section. A bend in the transition region may include a plate between the two signal conductors and the ground plane.