Will someone please tell me why the central locking range on a car doubles when you put the key to your headp?

i saw this on top gear and was amazed, i need to know the logic to it as i have baffled myself|||Your body becomes a large antenna which extends the signal range of the transmitter....I use to hold my remote start under my chin to get the same effect if my car was parked to far away. Metacafe has a video of how to mod a remote with a small strip of tinfoil too.|||Maybe it's that metal plate in your head acting as an antenna.