Dispersion characteristics of ultra wideband antennas and their radiation patterns

Ultra wideband (UWB) is a wireless technology to realize high speed communications which is performed in a wideband. However, the dispersion characteristics of antennas change seriously in the wide frequency band. Distortion arising from the dispersion reduces communication quality. In this paper, we numerically analyze the dispersion characteristics of linearly tapered slot antenna (LTSA) and Vivaldi antenna. We found that there exists a close relationship between the dispersion changes and the radiation patterns, in particular the null direction and its movement in the direction.