In this letter, a compact, frequency-reconfigurable antenna with a wide tuning range is proposed. It consists of a folded monopole structure, a transparent dielectric loading, and a varactor diode. The use of a water layer and a holder as the transparent dielectric loading can effectively reduce the antenna size, while keeping the antenna with a reasonable bandwidth and high efficiency. This new antenna occupies a compact volume of 17×14×4 mm3 (0.0237λ×0.0196λ×0.006λ at 419 MHz). By controlling the dc voltage over the varactor diode, the operating frequency of the antenna can be continuously tuned from 419 to 883 MHz, which is a very wide tuning band for an electrically small antenna. Both the computer simulation and measurement are conducted. The results demonstrate that it is a very promising candidate for hand-portable devices.