Patent ID: 8193880

Claim:
A device comprising: a substrate; a coplanar waveguide in a first layer over the substrate, the coplanar waveguide having a length and comprising: a signal line proximate to the substrate and coupled to a wave source, the signal line comprising a first conductive material and having a first side and a second side, the second side being opposite the first side; a first insulator proximate to the substrate and to the first side of the signal line and comprising a first dielectric material; a second insulator proximate to the substrate and to the second side of the signal line and comprising a second dielectric material; a first ground line proximate to the substrate and to the first insulator and comprising a second conductive material; and a second ground line proximate to the substrate and to the second insulator and comprising a third conductive material; and a dielectric layer between the substrate and the coplanar waveguide; wherein the coplanar waveguide has a first transverse cross-section that varies over its length; wherein the first and second ground lines respectively have second and third transverse cross-sections that are uniform over their lengths; wherein the signal line comprises periodically alternating first and second segments, the first segment being wider than the second segment; and wherein a first distance between the signal line and the first ground line varies along the length of the coplanar waveguide, a second distance between the signal line and the second ground line varies along the length of the coplanar waveguide, and the first distance is equal to the second distance at each point along the length of the coplanar waveguide.