HFSS Horn Simulation Error

Hi everyone,

I have a problem with my antenna horn simulation. Basically, i'm simulating an existing horn antenna, get the near field and then do the transformation for the far field.

However, I couldn't get the simulation to work in the first place.

First, I get this warning "given the specified frequency and model dimensions, an extremely large mesh is required to get an accurate solution." The edges of the radiation box are all more than λ/4 away from the aperture. the face right across the aperture is at least 2λ away, just like how it prescribes in the balanis text.

disregarding the warning, i went on to simulate. the simulation was stopped. the error message was "adaptive solution, process solver died unexpectedly."

What could I have done wrong?

Here's a link to a screenshot of what i have so far.

Thanks!
../imgqa/eboard/EM/EM-bdrgnj0xqez.jpg

use symmetric boundaries to simplify the mesh