I have a question for my project (HFSS v11)

Hi all. There is my project in attachment. This is a coax-waveguide junction. In practice it SWR is 1.1 in 10.5 - 10.65 GHz band. But, when I build model of this junction SWR is very bad. I'm a beginner in use of HFSS. Tell me, please, in detail, where is my mistake? Thank you very much for your helping!

Can anybody help me?

I simulated your project. Indeed the S11 gets only to about -6dB. I've tried to improve the meshing around the feed but the return loss did not improve. Are you sure that your built device and model are really the same?

Certainly, I've built my model for that graphics, which is really work, but, I'm a beginner in HFSS, may be I did mistake in this program, can verify it?

Actually, I think that you've set the hfss correctly. Practically I did no modifications to your hfss file, but I'm not an expert myself ;)

You HFSS model looks as unmatched. At least the distance to back wall should be around l/4 , while in your drawings it's about l/3. The distance from the waveguide bottom to matching cylinder looks to much as well.
Then the coaxial with glass filling. Are you shure that you are using exact one with eps=5.5 ? I never seen the rf coaxial cable with glass filling.
And you don't need to simulate full geometry, cut it by ZX plane and assign PerfectH boundary.