FSS lens array in CST - help needed

Hello friends,
I am trying to design a FSS lens array with CST. My aim is to have a Planar FSS array sheet which can focus an incident wave from one side to another side of FSS.
Does anyone have any idea how to proceed? It would be helpful if someone share some papers/CST models in similar area. I'll update the post as soon as I find something interesting.
Regards
Praful

what is the meaning ,i can not really understand! what is the property of the desired FSS

Just so I understand, you are trying to use the lens to filter out all other frequencies other than the desired? Or are you trying to make a lens?

Hi bconnor,
I am trying to make a planar FSS lens which work at single frequency.
Have you got any idea?
Regards

I think optimization is needed to design FSS.
PS:
I also very interested in fss design with cst. you can also refer a fss design available in cst tutorial. but my problem is how the dimension of the unit cell is decided.