A Transparent Dielectric-Loaded Reconfigurable Antenna With a Wide Tuning Range

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 of17 × 14 × 4\ mm³(0.0237 λ × 0.0196λ × 0.006λat 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.