Communication systems usually require smaller antenna size in order to meet the miniaturization requirements of radio-frequency units [I]. It is a well-known fact that planar slot antennas present really's appealing physical features, such as simple structure, small size, and low cost. In this paper, a novel Ultra-Wide Band (UWB) slot antenna with frequency band-stop performance is designed and manufactured. The fabricated antenna has the frequency band of 3.01 to more than 11.07 GHz with a rejection band around 5-6 GHz. Good VSWR and radiation pattern characteristics are obtained in the frequency band of interest.