As the conventional notched antennas realize band-notched characteristic only at a single frequency, amicrostrip-fed notched ultra-wideband (UWB) antenna with controllable notched bandwidths and a high rectangulardegree is proposed and implemented by using open-end slots. The band-notched characteristic is realized by addingtwo L-shaped open-end slots on the U-shaped radiator patch and one U-shaped slit on the feed line of the proposedantenna, and the notched bandwidths are controlled by adjusting the coupling distance between the slots and theslit. With these schemes, the proposed antenna achieves a well-matched broadband impedance in the bandwidthregion of 3.1 ~10.6GHz except the rejection bandwidth region of 5.1 ~ 5.8GHz. The time-domain behaviors of theproposed antenna are then analyzed and the correlation coefficient as well as the pulse-width stretch ratio is calculated.The measured results accord well with the simulated ones, which means that the proposed antenna is suitable forUWB applications.