Electronic article surveillance (EAS):
These can use an Electromagnetic (EM) system.
A mixture of low-frequency (in the 10 Hz to 1000 Hz range) magnetic fields are sent from a transmitter on one side of the door thru the tag to a receiver on the other side.
It detects a different frequency pattern when the low frequency magnetic field passes thru the tag that is magnetized.
This strip is not removed at checkout -- it's simply deactivated by a scanner that uses a specific highly intense magnetic field to magnetize the steel in the tag.
The electromagnetic tag is actually a metal wire or ribbon that has high permeability, making it easy for magnetic signals to flow through it.
See How Anti-shoplifting Devices Work
Acousto-magnetic systems (AM):
The detectors for such tags emit periodic tonal bursts
at about 58 kHz, causing the strip to vibrate longitudinally
which induces an AC voltage in the receiver antenna.
Ultra Strip® III Sensormatic DR tab
These tags have two metal strips, a ferromagnetic .magnetostrictive.strip which changes shape in a magnetic field and a bias magnet material.
They are called Dual Resonator (DR) tags.
When the AM tag is demagnetized, it is deactivated.
The popular SuperTags (alligators) used in clothing stores use AM technology.
A detacher tool at check-out removes the tag.
Radio-frequency (RF) systems:
Small flat tags with a LC (Inductor-Capicator) circuit are also used.
The LC circuit has a resonance frequency (usually around 8.2 MHz) which modifies the signal sent from the transmitter.
A device at checkout destroys the circuit.
Source Tagging is the embedding of disposable RF security labels at either the point of manufacture or packaging.
The newest source tags are paper-thin and easily integrated into automated production processes. These tags are applied in primary packaging (or within or on the product itself -- for example, incorporated into woven garment tags) and under labels on bottles.
Radio Frequency ID tags are also used. See RFID
Electronic article surveillance - Wikipedia
Electronic article surveillance (EAS) systems. What is an EAS system. Types of EAS systems. How EAS systems work.
last updated 6 Apr 2015