Dielectric lens antenna simulation in FEKO

Hi,

I am trying to simulate a dielectric lens antenna in FEKO. I have used two different approaches. 1. Importing radation pattern of a patch antenna and then using the impported pattern as the point source to illuminate the lens , 2. I simulate both the patch and the lens together using hybrid simulation method (MoM for patch and GO for the lens). The first method works but I don't see any big change in patch gain. The second method doesn't work giving the error message that GO can't work with waveguide port (I used waveguide port to excite the patch, I couldn't use any other). My problems are following:

1. What could be the possible reason that the lens doesn't show any big difference in gain?

2. When simulating both, do I need to perform any kind of coupling between them?

3. Is it possible to get s-parameters from the lens , while using the imported radiation pattern with the lens?

I really need some helps in these problems. Thanks in advance.

Regards,
R.A.