The progressive development of Ultra Wide Band (UWB) antennas and microelectronics allows for a wide range of future UWB radio communication applications. The paper focuses on testing and measuring various antennas and propagation aspects important in UWB radio. The ‘Delft approach’ of measuring UWB antennas using time-domain measurement techniques is explained including the diagnostics of antenna mismatch and wave scattering from the inside and the antennas environment. The approach is illustrated with measurements.