Substrate integrated waveguide cavity backed dumbbell shaped slot antenna

I am trying to design a substrate integrated waveguide slot antenna. I am following the paper attached herewith. I am new in this domain and so facing a lot of problems. Any help would be greatly appreciated. I request someone to see my .hfss file which I have made so far and help me by updating and correcting it.

Maybe posting two main problem description would get more answers, post some pictures of your results (S11, etc.). What do you want to achieve, which frequencies, what substrate, picture of your design (not everyone have HFSS here). I suggest not using dumbbell antenna. Why not using simple SIW with two different slots? It can easily met many requirements. For two frequencies SIW horn antenna would be also applicable.