Mutual coupling effect on bandwidth of Vivaldi arrays

In this paper, a two-element Vivaldi array has been designed with a quarter wavelength element aperture height regarding to the lower operating frequency, which demonstrates that the lower operating frequency of a Vivaldi array can be reduced by evoking appropriate mutule coupling between elements over lower frequency band. The results also suggest that mutual coupling should be a significant factor to take into account in phased Vivaldi array systems.