As I mentioned, there are ways of altering or disguising the length. The antenna on the transmitter may be a metal loop inside the transmitter housing, a short length of wire protruding or hanging from it or it may be included in the microphone cable. It may be electrically lengthened by the inclusion of an inductor in the transmitter housing or some combination of these techniques. It is therefore, not useful to measure the transmitter antenna.
Whether any attempt has been made to secure the channel depends on the budget of the purchasing agent, their previous experience with hooliganism like you propose, and other variables we can't know. I wouldn't expect it at a small educational institution, but you never know.
You must realize by now that if you put this kind of effort into your studies, you would be getting a better kind of attention from your professor.:razz: