How many length of discrete port while simulates dipole

Hi, my friends, I have a question about the dipole antenna simulation by CST.
When we designe a dipole antenna, the length of diple has been given such as 10mm. In cst we can use discret port. For example,we designe a brike(PEC)
and it will be subtructed by 10mm dipole.Then how we designe the length subtructed using as our .discrete port .And how the length effect the dipole antenna resonate frequnce ....S11 ...?

So my question is how to set up the length for cst accuracy simulation?
For my mother language isn't English, please don't mind my poor English!
Thanks
Wish best luck

if your length is not very long, it won't have a great impact on the resonance frequency of the antenna. But do not try to make it very thin, or you will have capacitive effects between the two poles of the dipole. I think a gap width of l/10 should be fine.