application UC-EBG in antenna

hi
I designed and created the dispersion digram for UC-EBG structure and get a band-gap of 9.5 to 11.1, when I place it between two antennas do not take the desired answer!!!!!!!

Antenna operating frequency is in the band-gap the UC-EBG.


What is my problem?
Can anyone help me?


Thanks

I would be interested in seeing why this did not work, did you use HFSS for design? Have you resolved this problem in the few months since you posted?

Now the problem is solved!

I used to design software CST MWS!

GOOd Luck