Impulse response with HFSS

Hello.

I need to obtain the electric and magnetic fields near an structure fed by an electrical impulse of nanoseconds (similar to lightning impulses). How can I simulate that with the standard excitations of HFSS?

Thank you very much.

I think, you need to use Maxwell_3D programme from Ansoft Company.

Can I solve the problem for several frequencies (fourier decomposition of impulse) and then add them in HFSS postprocessor? Anybody has done something like that?