[ltc8k6]

Passive RFID seems impractical for use in tracking. It’s range is too short. It could, at best, record when you pass through a doorway or pass close by a receiver.

You’d need to implant an active powered tag to actually track anyone from any distance, I’d think.

[Svartalfiar]

Passive RFID seems impractical for use in tracking. It’s range is too short. It could, at best, record when you pass through a doorway or pass close by a receiver.

You’d need to implant an active powered tag to actually track anyone from any distance, I’d think.

Yes, anything like this (many warehouses use RFID tracking on inventory coming in and out) is almost always going to need to be a passive chip. An active RFID is going to need some kind of power source like a battery. If it's implanted, what battery is small enough but strong enough to be implanted and still work? How do you change it out when it gets low? To get any kind of signal out farther than a couple inches, you need a pretty hefty power source. Are you just gonna have to wear an armband that holds a couple D-cells and plugs into a wire they leave sticking out of your arm?