If you have a car whose doors open when they approach the vehicle and close when they get away from it, be careful.
The cars that operate in this way use a low frequency signal that opens the doors when the owner is 20 steps or less and closes them when overcoming this distance. However, an experiment conducted at the University of Zurich ETH over 10 models of controls other than 8 different brands, has shown that using two anteneas signal amplifiers, lovers of others can expand this distance and keep it open, as well as start even if the owner moves away. Thanks to this the theft of the vehicle is facilitated.