As others have commented, it is a security device used in retail outlets (shpos etc). The outside metallic spiral is a coil and the square in the centre is a capacitor. When exposed to an alternating magntic field of a certain frequency, the circuit will resonate causing more current to be drawn fron the close proximity transmitting coil mounted in those posts either side of the shop dorway. This then triggers the alarm.

They are deactivated by being exposed to a strong alternating magnetic field on the shop checkout counter, this induces a high voltage in the coil which destroys the dielectric in the capacitor, it short circuits and no longer resonates. The stick on label on the checkout counter asking you 'Do not to put your credit card here' is the site of the deactivator, it also damages your credit card. Thanks for taking the time to include a photo and not a link.

It is so you cannot sneak out without paying. Many books and clothes have these things or similar added by the retailer. Usually they set off an alarm, and are usually but not always disabled at the point of sale, after you have paid. My thought is don't carry it around with you into shops, in case it wasn't disabled.

This is the one used in hypermarkets to control stealing from the shop. If this is not deactivated by the counter person when you make the exit there will be audible alarm. It is some kind of RFID

It's a coil for a planer transformer.

It may be a patch antenna or an RFID.

anything sifnificant?



http://www.flickr.com/photos/35279511@N07/11167031314/lightbox/