Thanks again Jian,
I've tried your suggestion for the top ground plane, but I have problem...
OK, here's how I add the infinite patch (top ground plane):
- first I add the dielectric layer (with its parameter ε and tanδ) says at X position, it become layer 1
- then I add the infinite top ground plane, the same method as the first one but in here I don't change the ε and tanδ, in substitute I change the real part of conductivity from 0 to 4.9e+007. I found problem for the Top surface, because when I input X+0.002 (the thickness of the ground plane metal), the system give me error mesage and didn't permit me to do that.Why?
When I choose the Top surface for the Top ground plane the same as the dielectric, i.e X it's accepted. But in the MGrid draw window ' didn't get anything (just white screen with grid), just like no metal at all. So when I try to add slot by using "Dig rectangular hole", don't give a result...
Please help me to do this, is just the same like simulating stacked slot microstrip antenna but the slot patch is infinite. That's I don't get it...
Thanks