A microstrip-fed ultra-wideband (UWB) antenna with a notched bandwidth by using open-ended slots is proposed and implemented. The notched bandwidth is realized by adding two open-ended slots on the U-shape radiator and one U-shape slit on the feed line of the proposed antenna. The UWB antenna is etched on 30 mm×36 mm substrate. The simulation and measurement show that the proposed antenna achieves a well-matched broadband impedance of 3.1–10.6 GHz (|S11|<−10dB), except the rejection bandwidth of 5.1–5.9 GHz (|S11|>−10dB). The antenna is successfully designed, simulated and measured with broadband matched impedance and near omnidirectional radiation patterns.