This paper reports a study of the influence on the fidelity factor due to loading an Ultra wideband monopole with a pair of dielectric substrate pads. The fidelity factor was calculated, with and without loading, using the simulated transmitted and received pulses in three points in the azimuth plane. Results show that this dielectric loading technique does not cause significant pulse distortion. The fidelity factor is affected only by an average of 2.8% relative to the unloaded antennas in all situations considered. Two versions of the same antenna design were studied: coplanar- and microstrip-fed. It was found that the influence of feeding on the fidelity factor is also minimal.