What is the best mesh define for a high εr patch?

I'm trying to rich the best accuracy for high εr(90) patch antenna.
When the mesh density control is changed from 25*20*50 to 50*30*50
The result changed dramatically.
So how can I know what is the best definitions for the mesh density control?
Does the adaptive mesh refinement can give me the right density?
Thanks in advance.[/code]

does anyone have any idea?

Hi, bbvv:

It seems to me you are using FDTD or similar scheme based EM simulator for your structure. They may not be accurate enough for high permittiivity structures. Normally, MOM simulators are more suitable for high permittivity structures. You can try IE3D for it (www.zeland.com). I am from Zeland. Regards.