Comparison of RF & AM Technologies

When an anti-theft tag enters the detection field of the antennas, a visual and/or audible alarm is triggered, alerting store personnel. At the time of purchase, the anti-theft devices are released or deactivated by the cashier. A store tag can also be self-alarming: in addition to the antenna alarm, the anti-theft accessory has its own alarming system that is automatically triggered if a thief tries to detach it or cut the cable.

Two main technologies are used today for the production of anti-theft equipment : radio-frequency and acousto-magnetic.

RADIO-FREQUENCY (RF)

Present mainly in grocery, textile, multi-media and convenience stores, or used largely for source protection, radio-frequency anti-theft devices are the most common on the market due to their efficiency and affordable price. They work thanks to radio waves (global standard of 8,2 MhZ) : a weak signal circulates between the two anti-theft antennas (in general a transmitting and a receiving antenna, but there are also mono antennas which can both transmit and receive signals). If an anti-theft accessory comes into contact with this signal, the frequency shifts and triggers the alarm.

RF labels, which are customizable, can be "deactivated" during the sales process thanks to a deactivation plate, a device placed on (or under) the checkout counter.

ACOUSTO-MAGNETIC (AM)

Acousto-magnetic, the most recent technology invented by the American company Sensormatic®, is generally recommended for department stores, luxury stores, pharmacies, perfume and cosmetics stores, or even DIY and gardening stores. This anti-theft system is popular for three reasons :

• It has a higher detection rate that can cover wide passages of up to 94 inches / 2.40 metres depending on the model ;
• The labels are small, offering a discreet anti-theft solution for the protection of small items;
• Also, this technology is particularly effective on aluminized packaging.

Acousto-magnetic anti-theft tags consist of 2 to 3 ferromagnetic stips generally based on a frequency of 58 KhZ. The principle is the same as for radio-frequency : when the accessories penetrate the detection field of antennas using the same frequency, the frequency increases, triggering the alarm. AM accessories can even work on non-ferrous metals, unlike RF tags that are neutralized by aluminized packaging.

To reinforce security in your store, it can sometimes be necessary to complete your anti-theft installation with systems capable of countering different theft techniques, such as aluminum linings in bags or clothing (using metal detectors).
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