Bow Tie antenna is a variant of a dipole. which is pretty similar to the design of dipole. but for your UWB applications, there are plenty of ways that can be adopted to get a UWB. Google for UWB bow tie and you will find plenty of papers on the topic like these
Two methods are used to increase bandwidth of a dipole. This is 1) a decrease of wave impedance and 2) an increase of radiation resistance.
The decrease of wave impedance of the dipole is used in bowtie antenna.