Improvement of an inverted microstrip line-based microwave tunable phase-shifter using liquid crystal

This paper deals with the study of electrically tunable phase-shifters based on the use of liquid crystals. First, the dielectric characterization of the commercial liquid crystal involved in our investigations allowed us to determine its dielectric anisotropy. Secondly, two phase-shifter configurations were studied. Both structures propose inverted microstrip line with coplanar accesses, but they are based on a different design of the transmission line. The measurements carried out with the first one evidenced an efficient phase shift. The second one showed considerable improvement in performances.