via holes in coplanar

I want to make via holes to connect sidegrounds and metal ground plate in grounded coplanar waveguide in CST. Can anyone help.

The only way I am trying is by making a cylinder and subtracting it from Ground plane.
Assuming you have FR4 PCB to be simulated as well, it will have to be 3 cylinders to be subtracted each layer.(top substrate and bottom layer)