A radio frequency circuit , comprising: a first dielectric substrate having a first surface; a second dielectric substrate having a second surface, the first and second dielectric substrates being positioned relative to one another such that the second surface faces the first surface; a transmission line formed from conductive cladding disposed upon the first surface, the transmission line being at least partially encapsulated between the first dielectric substrate and the second dielectric substrate; a pair of reference conductors , each of the pair of reference conductors positioned adjacent to and co-planar with the transmission line and spaced such that there is a gap between each of the pair of reference conductors and the transmission line, each of the pair of reference conductors disposed upon the first surface or the second surface and being at least partially encapsulated between the first dielectric substrate and the second dielectric substrate; a first ground plane provided on a third surface of the first dielectric substrate, the third surface being an opposing and substantially parallel surface to the first surface, and a second ground plane provided on a fourth surface of the second dielectric substrate, the fourth surface being an opposing and substantially parallel surface to the second surface, each of the first ground plane and the second ground plane being substantially parallel to the other and to the co-planar arrangement of the transmission line and the pair of reference conductors; and a trench formed through the first dielectric substrate and the second dielectric substrate, the trench extending between and being substantially perpendicular to the first ground plane and the second ground plane, wherein the trench does not pierce the first ground plane, wherein a conductive material is filled in the trench, and wherein the conductive material is arranged to be in electrical contact with each of the first ground plane and the second ground plane. a first dielectric substrate having a first surface; a second dielectric substrate having a second surface, the first and second dielectric substrates being positioned relative to one another such that the second surface faces the first surface; a transmission line formed from conductive cladding disposed upon the first surface, the transmission line being at least partially encapsulated between the first dielectric substrate and the second dielectric substrate; a pair of reference conductors , each of the pair of reference conductors positioned adjacent to and co-planar with the transmission line and spaced such that there is a gap between each of the pair of reference conductors and the transmission line, each of the pair of reference conductors disposed upon the first surface or the second surface and being at least partially encapsulated between the first dielectric substrate and the second dielectric substrate; a first ground plane provided on a third surface of the first dielectric substrate, the third surface being an opposing and substantially parallel surface to the first surface, and a second ground plane provided on a fourth surface of the second dielectric substrate, the fourth surface being an opposing and substantially parallel surface to the second surface, each of the first ground plane and the second ground plane being substantially parallel to the other and to the co-planar arrangement of the transmission line and the pair of reference conductors; and a trench formed through the first dielectric substrate and the second dielectric substrate, the trench extending between and being substantially perpendicular to the first ground plane and the second ground plane, wherein the trench does not pierce the first ground plane, wherein a conductive material is filled in the trench, and wherein the conductive material is arranged to be in electrical contact with each of the first ground plane and the second ground plane. <EOS>