Tunable Band-notched Ultra Wideband (UWB) Planar Monopole Antennas Using Varactor

A new tunable band-notched ultra wideband (UWB) planar monopole antenna is presented. The proposed antenna consists of a wideband planar monopole antenna, resonating stubs and varactor diodes. In order to generate tunable band-notched characteristic, we applied quarter-wavelength stubs with varactor diode to the wideband planar monopole antenna. We interpret the mechanism for notch characteristics using surface current distributions. This new approach is suitable for designing wideband antenna with narrow band interferer rejection characteristics.