HFSS complex impedance port setting

I don't know how to set the port impedance to be complex value for simulation of RFID tag antenna?

I want to use RFID chip which has the impedance of 12-j140. For the conjugate matching, I need to set the port impedance 12+j140.

However, the port impedance setting of HFSS only allows me to choose 50 ohms, not the complex value of 12+j140.

From the HFSS-Excitations-Assign_lumped port, I can only choose 50 ohms. How can I choose 12+j140? Thanks.

HFSS will compute the frequency response of the structure with 50 Ohm Zo first then if you wish, it will compute in according with your terminal impedance.

Go to HFSS/design settings/S parameter definition - choose "power".
You can also specify complex impedance defining the impedance as: 12 +1i*140. this should work (from 18.1 I think)