ractangular waveguide slot antenna array design using HFSS

Hi Dear all
I have designed a rectangular waveguide slot antenna using HFSS and paper below:
design and experiment on substrate integrated waveguide resonant slot array antenna at KU-band. By: Zi-bin weng et al.
My problem is that figures of return loss, E-plane and H-plane radiation is not true. I have attached my simulation HFSS file and reference paper, please help me if you can.
of course if running my HFSS file takes too long you can change number of iteration, max delta S and ....
I waiting for your answer.
Regards

Please help meeeeeeeeeeeeeeee