How to design paraboic shape in CST? just the reflector shape

i am planning to design a VSAT antenna.... i managed to make a horn antenna....now just need to add a reflector in front of this....Please can anyone describe me the geometry of Paraboic shape in CST? or what kind of extrude curve i have to use....this must be a great help for my personal projects. only the physical reflector design i am searching for .:) thanks in advance.

Use the conventional equation y=const* (x^2) and plot out the curves manually. Use different values for the const to get different shapes. Then make a template and use that ...