A new compact coplanar-fed antenna suitable for polarization diversity in ultra-wideband applications is presented. The antenna consists of two identical monopoles which are printed on a low-loss substrate with 3 mm spacing and positioned perpendicular to each other. Both frequency- and time-domain results have been measured and presented to validate the design. Results show that the proposed antenna has not only ultra-wide bandwidth (~115% for port 1 and ~107% for port 2) but also good port isolation above 22 dB over the entire band of interest. Moreover, radiation patterns demonstrate good orthogonal polarization operation. Furthermore, the system fidelity factor is adequate for pulse transmission with averages of 85% and 75% for port 1 and 2, respectively. Finally, the envelope correlation coefficient (ρe) has been calculated to evaluate the diversity performance. Results indicate that ρe ≤ -20 dB across the ultra-wide bandwidth. These results show the suitability of the proposed antenna for future UWB diversity applications.