We present a novel printed monopole antenna for ultra wideband applications. The proposed antenna consists of a square radiating patch with an inverted T-shaped slot and a ground plane with an inverted T-shaped conductor-backed plane, which provides a wide usable fractional bandwidth of more than 130% (2.91-14.1 GHz). By cutting a modified inverted T-shaped slot with variable dimensions on the radiating patch and also by inserting an inverted T-shaped conductor-backed plane, additional resonances are excited and hence much wider impedance bandwidth can be produced, especially at the higher band. The designed antenna has a small size of 12 × 18 mm2 . Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range.