Models of radio channel propagation are indispensable in the analysis and design of wireless communication systems. They are used to predict power and interference levels and analyze other properties of the radio link. In this paper we present a statistical model for the ultra-wideband (UWB) channel. The measurements are provided over channel bandwidth from 3 to 9 GHz in different environments. Based on a set of measurements in Indoor, Corridor and Outdoor conducted recently at Eurecom Institute, we find that the Weibull pdf fits well to experimental measurements. Also, an investigation of UWB channel dispersion properties is given. Finally, we found that the conventional narrowband systems.