In this paper, we investigated the radiation properties of novel planar monopole antenna with half-circular perturbations for ultra wideband (UWB) application. The proposed antenna, designed on low cost substrate material FR4, consists of a simple rectangular radiating patch with two half-circular cuts and a partial ground plane with a number of half-circular protuberances and cuts. The antenna is designed to operate from 1.85 GHz to 16.8 GHz and to achieve reflection of more than 10 dB. Good impedance matching, radiation pattern characteristics and constant efficiency are obtained in the frequency band of interest.