n What is RFID?
RFID, a contraction for Radio Frequency Identification, is a generic term for technologies that use radio waves to automatically identify individual items over relatively short distances (a few inches to hundreds of feet). RFID is a proven technology that’s been around since the Second World War.

Radio waves travel through most non-metallic materials, so the RFID tags can be embedded in packaging or encased in protective plastic for weather-proofing and greater durability. The technology had been expensive and therefore limited applications were available. But tags are being made cheaply now.

n What is an RFID tag?
An RFID tag consists of a microchip that is used to store a serial number that identifies a product, and some other information. The microchip is attached to a small antenna that enables the transmission of information to the RFID reader. Together the chip and the antenna are referred to as an RFID tag or an RFID transponder.

n What are active and passive tags?
The electrical power to drive the tag’s communication capability can either be derived from the incident radiation arriving from the reader or by an electrical supply source (e.g., a battery) located on the tag.

Tags, which derive their transmitting power from the radiation impinging on the tag, are known as passive devices. A tag that uses electric field to power it up is referred to as backscatter or reflective tag and usually utilizes higher frequencies and achieves longer communication distances.

When the tag has its own power source for transmission, those tags are referred to as active tags and can usually achieve even longer distance communication.

n How does an RFID system work?
The system consists of a tag and a reader with an antenna, also known as an interrogator. The RFID reader communicates with a tag through the use of radio frequency (RF) energy. The reader sends out an RF signal and the tag then modulates the waves and sends them back to the reader. The reader converts these new waves into digital data.

In addition to reading the tag, the reader can use RF energy to write new information to the tag. This enables the user to alter the information stored in the tag from a distance. The readers can be networked together so as to provide nearly unlimited coverage for a system.

n How much information can the tag store?
It depends on the vendor and the application, but typically a passive tag would carry about 2kB of data – enough to store some basic information about the item it is on. An active tag, on the other hand, can hold a lot more information than passive tag.

n How much will it cost me?
RFID attendance or access control cards are commonplace, and cheap: around Rs 50 to 80 each. Active tags are pricier: $50 to $90, but they’re reusable. The cost of the entire system is dependent on the application it is being used for. RFID readers for attendance or access systems start at Rs 25,000.

n Where can I use it?
The primary applications fall into two basic categories, direct product identification and carrier identification.

In the former, the tag specifically identifies the item to which it is attached (e.g., by part number or serial number)

In carrier identification the content is identified manually (or with a bar code reader) and fed to the control system along with the carrier’s machine-readable RF "license plate number." Strategically deployed RF readers enable subsequent load tracking.

Common areas of application include logistics, inventory control, article surveillance, access control, item tracking and in animal husbandry.

n Who can I buy from?
See sidebar: RFID Sources, on page 22.

n Why should I use RFID?
Most large companies are already using RFID-based attendance or access control systems. In the supply chain or distribution, RFID makes identification, location and tracking of items easy and real time. In certain areas the application has a direct impact on revenue. Gillette is using it to control shelf stock outs and shoplifting. 

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