This paper is focused on the study and applications of tunable composite right/left handed transmission lines (CRLH TL) based on open resonators. Specifically, it will be demonstrated that CRLH TL based on open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs) can be tuned by means of barium-strontium-titanate thick-films. These artificial lines are applied to the design of tunable band-pass filters, phase shifters, dual-band impedance inverters and dual-band power dividers, where independent or simultaneous tuning of different resonators can be considered, depending on the application. The design methodology and different proof-of-concept demonstrators are reported. © The Institution of Engineering and Technology 2013.