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.

Here's a site with a few different wifi antenna designs and some antenna modeling: http://www.lincomatic.com/wireless/homebrewant.html

This site has a calculator for cantenna dimensions: http://www.wikarekare.org/Antenna/WaveguideCan.html

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.

My mistake for misinterpreting the question.