How to set the impedance of discrete Port in CST2008 MWS

Discrete port in S-parameter type was selected in designing an antenna using CST2008 Microwave studio. The default impedance of discrete port is 50 Ohm. What should I do to set the impedance to 13+j151 Ohm?

I'm not sure but I don't think you can use complex impedance for the discrete port. Maybe just take the magnitude of impedance?
Z = R +jX ... since you have a positive value, you are dealing with an inductive reactance. |Z| = sqrt( R^2 + X^2 ) = 151.55 Ohms.
Or use lumped components in the 3D model...
Or use the 50 ohm port and then use the PSpice circuit schematic included in the CST project to place discrete elements, resistor and inductor, attached to port 1...
All I can think... but I need more information to help you further...
Lee