need help oh HFSS design

If i have understood correctly....
Is s11 in the present simln = 0.
Cover the entire structure with a box and deine it as vaccuum.
Is s11

I have only used this program a little bit but I don't think your ports will work as you have them. If you use lumped ports, then you need to draw a rectangle from the bottom edge of the package pins to ground. For your port 1 and 4, you can draw it in the xz plane so they touch the bottom of the box. For port 2 and 3 since they are far above the ground plane, I would draw them in the xy plane so the touch the vertical wall of the box.

Remember anywhere you do not have a dielectric, it assume a box of perfect ground.