KC
Jamming signals yes but why risk conflicts with the avionics.
Discarded a phone distructing jam signal on the jetway because you know how the legal eagles would love to have their Fone Killed - and who would get taken to the cleaners - the airlines.
No I still think a sensing device up near the start of the jetway, catch them while boarding best fits the common sense and learning patterns of "log headed" PAX.