About the Q factor of Spiral Balun

What should I note when i simulate the Q of Spiral balun by hfss or ADS?
The function is im part over real part , but what do it base on?
Should i short the second terminal in primary part ?

Don't short, terminate with a proper impedance (or resistance).

Hello~thanks for your reply.I have some questions.
Do you mean that Spiral Balun have four port?
The primary part have input and output,also secondary part do?
Then i need to set four lump port?