antenna matching with load

when i design a antenna by IE3D, i setup a load impedance for matching.
cause the antenna is only one port.

now i want to simulate that load in ADS.

in s-parameter there are two Terms/Ports in Schematic. so i don't know what term impedance is right for this setup.

for example, if the antenna impedance is 300+100j , then the load is 300-100j for matching.

if i simulate this load in ADS with two Terms. what value is right for each of this Term impedance value? in other words, the load matching the antenna, from the equivalent view, the load matching the two Terms in ADS. and i want to know what the Term value is right for equivalent.

From my view, the Term should half value of the antenna impedance for matching. it is 150+50j, but i am really not sure.

i am confused about this concept, so please hlep me figure it out, thanks.