I'm not sure by your reply if you are having the same problem I am or not. I will say that it doesn't seem to be directly related to a problem with the number of tets in the mesh. If I do not set any initial mesh settings and let it run until the memory is maxed, the radiation pattern is good (although possibly not convered). I only notice a problem when I set a (too?) fine initial mesh. In both cases, however, the final number of tets is approximately the same.
John