Sleeve Dipole Antenna Problem (HELP)

Hi guys

I simulated a sleeve dipole antenna and then build it. Its reflection loss was very wide as I desired. In the simulation I only saw a narrow bandwidth with one notch but the measurement showed a wide band response with two notches.
I Simulated the antenna using FEKO and HFSS.

How can I see the second notch in the simulation?

Thanks a lot.

Is the second notch a strong one? Have you incorporated conductivity into your models? I most suspect something is dampening that second resonance in your experimental that you have not considered in the model.