Design of filtering tunable liquid crystal phase shifter based on coplanar waveguide and split-ring resonators

Abstract

ABSTRACTIn this paper, the designing method for microwave filtering tunable liquid crystal phase shifter (LCPS) is proposed for the first time. The proposed microwave filtering tunable LCPS integrated tunable phase shifter and passband filter can simultaneously provide tunable differential phase shifts and self-embedded stable filtering function. This filtering tunable LCPS is based on the coplanar waveguide (CPW) magnetically coupled with a series of split-ring resonators (SRRs). On this basis, the equivalent circuit model is utilized to analyse the relationship between stable filtering characteristic and tunable differential phase shifts. Finally, the prototype samples are fabricated and tested. The measured results not only show that the proposed filtering tunable LCPS realizes the stable passband from 7.9 to 8.2 GHz but also indicate that the differential phase shifts and figure of merit are, respectively, more than 55° and 9.6°/dB in the passband, which provide a good verification for the theoretical concepts.