urgent: PIN diode modelling in HFSS

Hi,
Can anybody guide me how to model diode in HFSS? I am not sure if it can be directly done using HFSS but is there other way that i can do it? I want to model diode to use it as switch in my antenna design.
Please consider it as urgent.

Thank you. Awaiting for your replies

-Ankesh

U can diode modelling in ADS..If u have the spice model.