Planar Multilateral Disc Monopole Antenna with Variable Band-Notch Function for Bluetooth/UWB Applications

A planar multilateral disc monopole antenna for ultrawideband (UWB) application is initially proposed. By asymmetrically reducing the ground plane structure, this proposed UWB antenna is able to integrate with the Bluetooth band, which provides a wide bandwidth from 2.27 to more than 12 GHz. In order to perform a rejection on the 5.2/5.8 GHz WLAN band signals, the technique of inserting an L-shaped stub into the microstrip feed line is proposed, and with the insertion of another L-shaped stub, a rejection on X-band signals is also achieved. All prototype antennas are theoretically and experimentally investigated, and the vital parameters such as the dimensions of the L-shaped stub for controlling the notched frequency and bandwidth are clearly illustrated. Near omni-directional patterns across the integrated Bluetooth and UWB bands with acceptable gain variation are measured, and good frequency domain characteristics are also observed, except in the notched band.