Types of EAS Systems

An EAS antenna contains an RF electronic circuit board system, which detects any

electronic security tags or soft labels that pass through it. An alarm sounds whenever a

tagged merchandise item is taken out of the store without these tags being deactivated

or removed at the checkout counter

EAS system include RF, electromagnetic, acousto-magnetic (AM), and microwave.

A magneto-harmonic EAS system consists of tags made from strips of an amorphous

metal. An amorphous metal is a metallic material in which the orientation of all atoms is

random without any order. When this tag is magnetized, all atoms are aligned in one

direction and when demagnetized, the atom again takes the random form. Detection of

the tag is achieved with both a transmitter and a receiver, which work on frequency

harmonics. The transmitter detects the ferromagnetic material and sends signal to the

receiver, which raises the alarm. Deactivation of these tags is done by magnetization

of the tag and activation requires magnetization. Due to the capability of the system to

reactivate and deactivate these tags, it is preferred in libraries.

An AM EAS system is also known as a magnetostrictive EAS system. The tags used in

this system are similar to those used in a magnetic EAS system, but are slightly

thicker. Magnetostriction is a property of ferromagnetic material that causes it to

change shape when subjected to a magnetic field. In this EAS system, the transmitters

deployed at the exit of retail outlets send signals at a frequency of 58 kHz periodically.

This transmitted frequency causes vibration in the tag that continues even after the

signal is stopped. When an item to which the tag is attached is brought to the detector

or the antenna of the EAS system, the receiver detects the frequency generated by the

vibration of ferromagnetic material present in the tag. If the signal generated through

the vibration matches with the frequency of the receiver, an alarm is triggered. AM EAS

systems are cheaper and have better accuracy than magnetic systems. 

RF systems

The tags used in RF EAS systems are LC circuits, which are made up of an inductor

and a capacitor. The resonance of the tags can take place anywhere between 1.75

MHz and 9.5 MHz, which is detected by the receiver and an alarm is raised. The

deactivation of these tags is done either by punching a hole in them or submitting them

to a strong electromagnetic field that exceeds the breakdown voltage of the capacitor

and partially destroys it.

Microwave systems

In a microwave-based EAS system, diodes are used as tags. Diodes conduct electric

current only in one direction. The antennas kept at the exit of the store generate two

types of signals. One is emitted at low frequency of 100 kHz field and the other is

generated at the microwave range of frequencies. The tag acts as a mixer and

combines both the frequency signals into a new signal called a modulated signal.

When this tag is brought near the exit antennas, the modulated signal produced by a

tag matches with the detector and raises an alarm. Microwave systems are costly and

are mostly used in the apparel and fashion accessories segment. 

RF EAS Systems are most commonly used by retailers and tend to be the least expensive. Works well for apparel, shoes, sporting goods.

AM EAS Systems work well for consumer electronic, home improvement, grocery and pharmaceuticals.a nice option in environments that have a lot of radio noise from other sources.

EM EAS Systems are the preferred choice of vendors of books and art supplies.