antenna with substrate of large thickness

I simulate an antenna with substrate of large thickness(more than 10mm at 10GHz), and use the infinite ground plane, and advanced extension port, so how can I set up the the port to avoid the warning " the substrate thickness factor for port is too big",and "the ground separation/length radio for port is too big", and could get the high simulation accuracy?

The input impedance of the antenna is not uniquely defined when your port to ground (or reference) distance is more than 10% of a wavelength. In some sense, it is similar to solving the input impedance of a dipole antenna when the gap between the 2 arms is very big. You can not get consistent result because it is not a consistent value. You can get different value depending upon how you measure it.

Sounds like you are using IE3D.

I have found that utilising a finite dielectric and finite ground plane scheme can make that error message disappear. However your simulation run time will increase by 10 fold.