Importing S parameters in CST or HFSS

I have strange capacitors(active and negative) and i have measured S parameters(touchstone format).
So i need to calculate far field of antenna using that capacitors. How can i import S parameters to cst microwave studio or HFSS. Like new lumped element, but not simple as RLC.
I tried with cst design studio, but i can only calculate S parameters of whole antenna, but not far field :(.
Any suggestion? Or different simulation program?

I have idea, but also problems :).
In frequency solver i can put luped elements are calculate values for every frequency(lot of work, but :) ). But i can't define negative R.
Any idea or software where i can define negative R and calculate farfield?

Use Ansoft Designer to bring in the HFSS project. Where you would have caps in HFSS, place lumped ports. The lumped ports will become pins in Designer (a circuit tool) where you can connect passive elements for a linear network analysis. This will calculate the S net S Parameter of the antenna at the feed in Designer...however then you can Push the Excitations to HFSS and then then observe the far fields in HFSS that are due to the circuit you have created. It is best if you contact an AE to help you with this for your first time...
have fun