S. Wang, X.D. Chen, C.G. Parini,  “Analysis of Ultra Wideband Antipodal Vivaldi Antenna Design", Antennas and Propagation Conference, 2007, Loughborough, 2-3 April 2007 Page(s):129 - 132

The publication is available to download from http://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=4218444&isYear=2007