ADS comparsion to 3-Dsimulator

when you draw a conductor in the 3D simulator then through the adjusting of the boundary conditions you can determine whether this conductor behaves like a T.L(here S12=0dB in case of two ports contected to the terminal of the conductors)or like an radiator atntenna(if you put the boundaries open then it will behave like a radiator).
but in the ads when you draw a conductors the it will behave allways like a T.L.
i dont trust the ADS results in designing an Antenna.
Am i right?


thanks