Eli5: how do anti theft radio frequency tags know i bought an item

Question

for context i just bought 3 bags of beef jerky from 5 below and they all had one of those square tags with the lines on them and i only scanned one 3 times at the self checkout how do they get deactivated

Edit [https://imgur.com/a/c3DFJFg](https://imgur.com/a/c3DFJFg) here’s a picture of it

In: Other

Answer 1

They’re destroyed at the register. A small amount of RF can activate an antenna attached to a chip that basically screams “I’m stolen” at the reader. You pass it over the deactivation pad and it just fries the chip completely. No RF signal is returned with “I’m stolen”.