Semi-Circular Stubs UWB Monopole Antenna with Tunable Dual Band-Notch Characteristics.

This paper proposes a tunable dual band-notched ultrawideband monopole antenna for ultrawideband applications. The proposed antenna consists of a circular ring monopole antenna as a main radiator with two unequally sized semi-circular stubs added near the inner edge of the circular ring to achieve dual bandnotching. The band-notching tuning is achieved by connecting the larger stub to the main radiator via a single varactor diode. The proposed antenna exhibits a wide impedance bandwidth from 2.8 to 21.9 GHz (154.6%), which is much wider than that of other published antennas. The center frequencies of the dual band-notched are simultaneously tuned using only one active element from 3.5 GHz to 3.8 GHz and from 6.7 GHz to 7.2 GHz, which can reject the WiMAX and the lower X-band applications. The measured results show good agreement with the simulation results. [ABSTRACT FROM AUTHOR]