A planar ultra-wideband monopole antenna with multiple notched bands characteristics is presented. The antenna satisfies the VSWR requirement of less than 2.0 in the frequency band between 2.84 and 12 GHz, except four frequency stop-bands of 3.2–4.1 GHz, 5.0–5.4 GHz, 5.79–6.07 GHz and 6.6–7.8 GHz. By employing a hookshaped defected ground structure (DGS) in each side of the ground plane, embedding an Ω-shaped slot on the radiating patch, adding a semi-octagon-shaped resonant ring on the back side of the antenna and etching a u-shaped slots beneath the feedline, multiple notched frequency bands are achieved. The antenna shows fairly stable radiation pattern, good group delay and transmission characteristics over the frequency range of interest. The fidelity (F) and the time window containing 90% of the transmitted energy (RE90) are resorted to estimate the time domain characteristics of the proposed antenna.