A frequency tunable resonator topology is proposed that consists of an S-shaped resonator, a ground frame and a feeding transmission line. Tunability is achieved by using reverse biased varactor diodes employed at critical locations on the structure. As well as being a tunable resonator, the structure also provides tunable metamaterial properties. Reflection and transmission parameters, electric and magnetic field distributions, and permittivity and permeability at each tuned frequency were analyzed and shown. Simulation and measured results agree well and demonstrate about 28% frequency tunability.