https://youtube.com/watch?v=TDJljGdxk4M%3Fversion%3D3%26rel%3D1%26fs%3D1%26autohide%3D2%26showsearch%3D0%26showinfo%3D1%26iv_load_policy%3D1%26wmode%3Dtransparent

It is a staple of spy movies. The hero — or sometimes the bad guy — sticks a device never any bigger than an Alka Seltzer to a vehicle or a person and then tracks it anywhere it goes in the world. Real world physics makes it hard to imagine a device like that for…

via Tiny Transmitter Tracks Targets — Hackaday