Simple circuit to find lost passport

can't

is

Most recently, pallet trackers, tag receives at ~130kHz, transmits at ~900MHz, battery-powered. Semi backs up to a loading dock, shipment details are read... range ~100 feet. ...Jim Thompson

can't

not

bugger is

to

way?

That would work. An alarm should sound if he gets that far from the bus from the home for the 'Mentally Decapitated". I wonder if his seat is next to Sloman's? ;-)

In their case,it is all the same, since most have the intelligence of a rock; the higher intelligence purveyors of malice to taxpayers are up to the intelligence of plants (weeds).

I don't quite see how that can work. At the very least one could record the initial interogation signal, and replay it near a passport. Encryption could then protect the content of the response, but not prevent detection of its existence, which is all the OP wants.

In other scenarios one builds in protection against replay attacks, but I don't see that being practical for a passport chip.

The US neglected to encrypt the video on its military surveillance drones, so why would they bother protecting the privacy of their citizens?

Sylvia.

Of course. It is a metal detector. I assumed that you hid your passport in less obvious place. Check you luggage.

-- Boris

the detection range will be a few centimetres.

It should be possible to get a longer range, but cost goes up dramatically for long range readers.

OTOH you might have success using a dip meter tuned to the resonant frequency of the RFID tag (13.56Mhz), Perhaps equipped with a loop antenna instead of the usual compact coil. I don't have a dip meter so I can't test it on a generic RFID tag here.

It just happens. passports use "IEC 14443" which operates at 13.56MHz

AIUI if the the card is using load modulation it shorts the antenna reflecting some half-cycles, in effect transmitting on a subharmonic