Antenna Feeding

When using software such as cst or feko is it necessary to simulate how the antenna is "excited". For example if i know i will be using a balun to connect a dipole antenna to a coax line do i need to simulate the balun with the coax or can i just use a port to excite the antenna. I am trying to determine if it is at all necessary. Any specific reasons why it would or would not need to be done?

I would simulate the connection method if the real life scenario was not ideal. Like a long cable run to the antenna that doesn't have access to a good ground at the base of the antenna or that you are aware of a missmatch that will take place and want to know its impact.. But if you have ideal conditions for your final application I wouldn't worry.