In this paper, a 4 £ 4 indoor Multiple-Input Multiple- Output Ultra-Wideband (MIMO-UWB) measurement campaign in the 2{5GHz bandwidth is presented. The main contribution of this work is the impact of radio-wave polarization as well as the efiect of frequency dependence on the capacity of MIMO-UWB systems working in an o-ce environment. To accomplish this, the capacity for difierent polarizations is analyzed under two difierent assumptions: constant or variable Signal-to-Noise Ratio.