The vertical displacement of a columnar fluidic colloidal dispersion is examined as a frequency reconfigurable dielectric resonator antenna (DRA). The coaxial probe-fed structure has tunable impedance properties that are reversibly controlled by adjusting the columnar height of the dispersion. Colloidal barium strontium titanate was dispersed in hydrotreated naphthenic oil and placed at several heights into a section of polycarbonate tubing over an aluminum ground plane to demonstrate the impedance properties of this structure. Measured, simulated, and calculated results for a range of heights that corresponded to single-mode operation are provided for a design operating between 2.5 and 4.5 GHz. \ 2010 IEEE.