Liquid crystal enabled substrate integrated waveguide variable phase shifter for millimeter-wave application at 60ghz and beyond

A variable phase shifter based on substrate integrated waveguide (SIW) and liquid crystal (LC) is proposed and demonstrated in 57-65GHz. The permittivity of nematic LCs can be made variable by applying various intensities of electric or magnetic fields. By partially replacing the dielectric substrate of SIW with standard LC (E7) and embedding an electric bias structure, an electronically tunable phase shifter is created. The phase shifter can be continuously tuned up to 300 ° with an insertion loss from 4.5dB to 8.5dB. Since alternative LC materials having a much lower loss tangent are already available, the results obtained from this experimental demonstration illuminate an emerging class of high-performance tunable millimeter-wave devices that can be seamlessly integrated in SIW platforms.