Optimization of S-parameters of microstrip patch antenna in CST

Hi everyone!

I design a patch antenna and I need that maximum level of S11 parameters would be low than -10dB.
No one of defaults optimizer's operators (min, max, <, > etc.) don't let me to make this goal.
How can I reach this? I heared something about User Defined Goals, but Gooogle doesn't give me more detailed information.

Thanks in advice