Packaged MEMS devices for RF applications have been modelled, realized and tested. In particular, RF MEMS single ohmic series switches (SPST) have been obtained on silicon high resistivity substrates and they have been integrated in alumina packages to get single-pole-double-thru (SPDT) and true-time-delay-line (TTDL) configurations. As a result, TTDLs for wide band operation, designed for the (6–18) GHz band, have been obtained, with predicted insertion losses less than 2 dB up to 14 GHz for the short path and 3 dB for the long path, and delay times in the order of 0.3–0.4 ns for the short path and 0.5–0.6 ns for the long path. The maximum differential delay time is in the order of 0.2 ns.