How to set up ground in HFSS?

Hi, guys, I am using HFSS to simulate a structure: it includes a parallel plate cavity sitting in a cone whose boundary is copper. Now I want to set the boundary of cone be ground and feed the parallel with coaxial cable? How can I do it?
the attachment is my sturcture. Thanks

In my structure: it is a parallel plate sitting in the cone, air filled inside cone, the boundary material of the cone is copper.

u can use via from up to bottom .

would y please describe your question with a graph,maybe i can help y

Hiiiiiiiiii loverain,
I think you can just assign the outer skin of your cone using a top to bottom approach as your ground using the Finite conductivity, Infinite ground option, it would be better if you can give graphical description of your problem, I can just think of this.