How to excite a Vivaldi antenna?

I have to design a Vivaldi Antenna. Can somebody suggest a book or article where I can read about it! Main problem is how do you excite vivaldi antenna Thanks!

see
http://www.mwrf.com/Articles/ArticleID/5419/5419.html

Thanks, but there's one thing that I can't find anywhere: how can I calculate Vivaldi antenna input impedance? I also found a dielectric transformer (Characterization of miniature millimetre-wave vivaldi antenna for local multipoint distribution service, Simons, Lee), but I don't understand how it works and what are its dimensions (in general, not just for a specific antenna).

hi
your answer

I also want to simulate vivaldi antenna, and I will the finite element method with my own algorithm.
but the most difficult task for me is to geometry modeling and mesh genernation.

would anyone give me some advice ? thanks !

EMC Studio: Vivaldi Antenna Example

You can try Method of Moments software for numerical simulation reference. Attaches is planar-triangular meshed Nastran file with this antenna.

can anybody tell me, how to tune stub in vivaldi antenna, and how it affects the bandwidth of antenna?