9.9Ghz patch antenna with CST

Hello guys,
I tried to design a 8*8 patch antenna array at 9.9 Ghz with CST and first i designed a single element.
i use the RO5880 Substrate with Er=2.2 and H=0.508 mm
i would like to know if my subtrate is the best to work at this frequency and to design this kind of antenna?
why when I simulate my ptach I narrive not get my point of resonance frequency on the axis of the real smith chart ?
Thanks for your help
Regards

RO5880 is reasonably good substrate. The best substrate is air - no dielectric losses.
Your 2d question is unclear. Simulation and measurement do not match? - could be many different reasons, more details needed to answer. First study many other posts on this board discussing the same problem.