How to set port impedance in HFSS to simulate RFID antenna

Hello, all friends here. I am very glad to find this forum where people are so enthusiastic and friendly.
I am confused by a RFID antenna simulation problem for many days. If the chip's impedance is 20-j160, the antenna designed should have a impedance of 20+j160 for max power transfor. However, in HFSS, version 10, the port impedance is 50 ohm.Can I set the port imepdance to be 20-j160 which is the impedance of the chip? If can't, how to set the port's impedance if I want to simulate the RFID antenna attached with a chip correctly.Especially the Gain, S11 and bandwith?

Here must be many people who are familar with the RFID antenna simulation using HFSS.Please help me and give your suggetstions. Thank you a lot.

Regards.

Review the material in HFSS help and pay particular attention to the differences between lumped and wave ports. Basically you can set a lumped port to a particular impedance and with care a wave port will tell you the actual impedance of your port.

What's your meaning ? I want to know what the port impedance should be when a RFID antenna attached with a complex impedance chip is simulated. It seems that 50 ohm is not very suitable for the port impedance.

Differences between lumped and wave ports?It seems that Lumped port is an alternative of wave ports when the port is placed in a structure.