Modelling a structure excited by line source in HFSS 9.2

I have a structure which is excited by a line current source parallel to z axis. The current varies along the line in the form of exp(-j.beta.z), where "beta" is a constant number. Now my quation is that how I can model this kind of current in HFSS9.2.

I wonder the answer to the same question for CST MWS

Can you put a sketch of the structure? I've done similar things by drawing a thin line and exciting it with a lumped port.