Suppose the height of the dielectric substrate is 50 mil and you want metallic inclusions say at a height of 25 mil from the ground plane.
Create the Stackup as follows:
Signal layer 2
dielectric (25 mil)
Signal layer 1
dilectric layer (25 mil)
ground
When i make your stackup i think there is a problem. When i desing the Signal layer 1 and make a structure on this trace layer , let's say for example one square, what is the surrounding of this square ? I need one inclusion in a dielectric layer !
Only the square metallic inclusion will be present in the signal layer 1. First try that stackup in Ansoft Designer, I used this kind of stackup for designing two layered structures in Ansoft designer and I am pretty sure that it will work.
I tried but i think it work not properly because the losses of my substrate are too high. I would like to subtract the layers like tony suggest, but actually i really don't know how to do it !