Different simulation results on HFSS11 and CST 2010

[bwana1]

Hi all,
It's about two months I'm looking for an explanation or an error of mine.
At first I have simulated a parametrized short backfire antenna on HFSS11 for the wifi band. Fo= 2.45 GHz.
After some optimization I achieved a VSWR between 1:1.3@ 2450
and 1:1.7@ 2400 and 2500 MHz with a directional gain of about 25 dBi.
This last value seemed to me too good when compared with internet literature.
So I decided to cross-test the same model using CST 2010 MWS.
This time the simulation yelded a completely out of tune VSWR around 1:160@ 2450 with a directional gain around 14 dB.
A larger frequency scan showed that, anyway, the 1:160 VSWR was a valley point.
I controlled the way I declared the ports (both simulations use microwave ports) but wasn't able to detect any error.
The most astonishing thing for me was that, while in the HFSS11 simulation a Smith plot of the antenna input impedance
vs frequency between 2.4 and 2.5 GHz shows near-coincident points at the 50 Ohm chart center, the CST simulation shows
an arc of the largest circumference instead.
Which one is the liar? I feel that both lie in some way but have no way to decide
Any hint will be highly appreciated.

 

[MSIQ]

hi,
although its too late...but do you that hfss file of short backfire antenna designed to operate at 2.4Ghz...if yes, than can you share it....because the antenna that i have designed in hfss (short backfire) is operateacle at 2.8Ghz and i want it to be at 2.4Ghz....if you have that file than do share....