Abstract An Ultra-wideband (UWB) microstrip antenna fed by a coplanar Waveguide (CPW) is proposed. The proposed antenna consists of a rectangular shape box embedded with semicircle slot in the patch. It occupies a total area of 39×36.275 mm2. It provides a wide impedance bandwidth of 7.39 GHz ranging from 2.66 GHz to 10.05 GHz. The parametric studies are performed to understand the characteristics of proposed antenna. The details of proposed ultra-wideband are described. The various antenna parameters like S-parameters, current distribution and radiation pattern are studied. The proposed antenna is also suitable for WLAN/WiMAX/ UWB applications. Keywords: Microstrip Antenna, WLAN, WI-MAX, UWB, CPW feed.