ansoft HFSS problem

hi all, does anyone has experience using HFSS to plot the antenna gain vs frequency? isit just sweeping the gainTotal vs freq? for my problem is tat my s11 is -2~3db at 20ghz but i get my maximum gain at 20Ghz. With theory, gain should be max at the range where s11 is well matched. Can anyone advise on this. Thanks

I believe the gain is irrevelant to the matching. From the power issue, it is determined by the radiated power to the power getting into the antenna, not the power reflected.

hi, thanks for replying to my problem. yesterday i tried to plot the gain vs frequency again. 1st time i tried ploting it when i finish simulating the antenna, the 2nd time was plotted the other day with the simulated results saved. But i got 2 different plot. The 1st plot is more reasonable, while the 2nd plot was way off. Did you experieced this before? Or , isit advised to delete the solution and resimulate then plot again?