UWB Antennas & HFSS

Dear Freinds,
I have tried to resimulate the same antenna as described in Parini's artilce (see attached file) but I can't succes to get the same S11.
can anyboady tell how we can choose the frequency center in HFSS when we simulate UWB antennas?

No one has an answer of this problem.
How we can simulate UWB antenna using HFSS?

Dear helio:
i will try to simulate it , since i am researching uwb antenna too.
my email: fanqikai@163.com
keep contact please.
rgz
kaka

hi helio:
simulating . ...
i will tell you the result by email.
best
kaka

Added after 24 minutes:

hi helio:
the result is not very good . though the S11 parameter is like the measured results , the high frequency is not so good , well , it may because i change the relitave CS and there is a warning pops up, i am not sure wheather it leads to the bad result.
well, i will use IE3d to re-simulate it .
kaka