No, and it's of no importance. It's just something that will make an electrical connection with the coil and stay there.
Edit: I answered the wrong question here, thought he was talking about the coat hanger I used in the crystal radio set. In the case of the WiFi antenna it matters a lot!
It certainly does matter, especially on the transmitting side. It's just hard to predict how long it needs to be without breaking out antenna modeling software.
Sorry, I was answering a different question (the original question was a bit unclear). The antenna length certainly does matter as you point out, I thought the parent was asking about the piece of coat hanger that I use to sweep along the coil to find stations in my crystal radio.
Edit: I answered the wrong question here, thought he was talking about the coat hanger I used in the crystal radio set. In the case of the WiFi antenna it matters a lot!