How to simulate EBG substrate with CST or IE3D?

First of all I introduce myself. I am a student doing my thesis working in Antenas Design, and i dont know a lot of things about it.
I have designed and simulated an antenna with the CST and IE3D software, using the Cuclad 217 as substrate.But in the next step i must use the EBG as substrate. Do you know how can I do this?
Do I need to do a lot of changes in my design? I dont know if there is a library in one of these programs to simulate this substrate
Thank you very much.

I don't know...?