simulation problems by Feko

Hello,
I need some help from Fεko professional. Ich simulate a thick dielectric lens antenna(diameter=40*lambda, tickness=100*lambda) using GO for dielectric and have following problems
1)How can i put a radiation source in the dielectric material?
2)Is it correct that GO for dielectric only usable for thin dielectric material?

There is a lens example in the examples folder, you can looking for it. I have only used feko to simulate bifocal lens, and the radiation source is the far field data of a horn simulated by hfss, I haven't simulated the dielectric lens as your diameters... but I think the GO method can apply to thick dielectric lens also, you can try it.