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RFID Basics

Radio Frequency Identification (RFID) is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify an object, animal, or person.

Evolution of RFID

In 1946, a Russian invented an espionage tool called the Covert Listening Device. This device retransmitted incident radio waves with audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, which modulated the reflected radio frequency. This passive device was attributed to be the first known device and a predecessor of the RFID technology.

The British invented a similar system during the World War II to identify enemy aircraft. It was called the identification of Friend or Foe (IFF).  In 1971, an RFID device that was passive, powered by the interrogating signal, with a 16-bit memory transponder was invented. This device was the true ancestor to modern RFID and was patented in 1973 in the USA that had demonstrated its uses in:

• Transportation (automotive vehicle identification, automatic toll system, electronic license plate,  electronic manifest, vehicle routing, vehicle performance monitoring)
• Banking (electronic check book, electronic credit card), security (personnel identification, automatic gates, surveillance)  
• Medical (identification, patient history)

How it works?

Radio Frequency Identification (RFID) is an automated object identification method that uses radio frequency technology.

RFID has three components: 

• An RFID reader, which provides power and interrogates the tag, then receives and processes information
• An RFID tag, which has an unique ID, with or without user memory; and, 
• An antenna, which converts electrical power to RF power. 

The reader sends out a radio signal and any tag (unique identifier of any item it is attached to) in the reading range sends out a signal to identify itself. The reader then converts the radio signals sent by the tag into data, which is then passed on to the processing system.  The data received from the reader is processed to filter, categorize, analyze, and enable actions based on the identified information.

Components of RFID

Tags

An RFID tag or transponder is a microchip combined with an antenna in a compact package. The packaging is structured to allow the RFID tag to be attached to an object to be tracked. The tag's antenna picks up signals from an RFID reader or scanner and then returns the signal, usually with some additional data (like a unique serial number or other customized information).

RFID tags can be very small - the size of a large rice grain. Others may be the size of a small paperback book.

The tag comprises the:

• Chip (IC)
• Antenna
• Packaging

The tag has an integrated circuit (IC), that contains the unique identifying data of the object to which it is attached. The IC is attached to a small antenna, which is commonly a small coil of wires.  These electronics are then packaged according to the requirement. Tags can take a variety of forms like:

• Smart labels
• Keys and Key fobs
• Watches
• Smart Cards
• Disks and Coins
• Mount-on-metal   
• Glass transponders

Types of tags

Tags are classified based on Power requirement and memory.
Based on power requirement, tags are classified as Active and Passive.  The difference between these are elicited in the table below:

Passive Tags	Active Tags
Operate without power	Operate on battery
Less expensive	More expensive
Unlimited life	Limited life
Light in weight	Heavier in weight
Less range (up to 3 to 5 meters)	Greater range (up to 100 meters)
Subject to noise	Better noise immunity
Derive power from the electromagnetic field generated by the reader	Internal power to transmit signal
Require powerful readers	Effective with less powerful readers
Low data transmission rate	High data transmission rate
Fewer tags can be read simultaneously	More tags can be read simultaneously
Greater orientation sensitivity	Less orientation sensitivity

Based on memory capabilities tags are classified as:

• Read only tags                The stored data can be read but cannot be changed
• Read/Write tags             These tags store data that can be altered or even re-written.

Readers

Reader Module

Handheld Reader

A reader is also called an interrogator. An RFID reader is a device that is used to interrogate an RFID tag. The reader has an antenna that emits radio waves to detect a tag in its reading range; the tag responds by sending back the data.

A number of factors can affect the distance at which a tag can be read (the read range). The frequency used for identification, the antenna gain, the orientation and polarization of the reader antenna and the transponder antenna, as well as the placement of the tag on the object to be identified will all have an impact on the RFID system’s read range. The reader either continuously (in case of fixed readers) or on demand (as in handheld readers) sends out electromagnetic waves to inquire the presence of any tags in its active read field. On receiving the signals from the tags, the reader decodes the signal and forwards it to the host information processing system.

RFID Frequencies

In RFID technology four frequency bands are used. The frequency band, description and range of these frequencies are given in the table below:

Frequency band	Description	Range
124 – 134 kHz	Low Frequency (LF)	Up to 18 inches
13.553 – 13.567MHz	High Frequency (HF)	2 inches to 10 feet
868 – 928 MHz	Ultra High Frequency (UHF)	10 to 30 feet
2.4 GHz	Microwave	> 10 feet

Applications

Current Uses

Some of the typical applications of RFID are in: 

Time and Attendance:  A contactless RFID card is shown in front of a RFID reader that identifies the person carrying the card and registers the date and time. The data from the reader is routed to the main computer system where the application program links it to the payroll application. 

Access Control:  The same RFID card can be flashed in front of a reader and this is linked to a relay that opens a barrier or an access door.

Asset Management:  Each asset, either movable or fixed, to be inventoried or tracked is tagged with a suitable RFID tag and the asset is tracked with Fixed or Handheld readers, whenever it is relocated from its original position. This technology helps in locating the required asset at any point of time.

Mass Transit/Bus & Train passes: The ticket/pass issued is an RFID card with unique ID and of a certain fare value with a validity period. When this card is shown to the RFID reader fixed at the entrance to the bus or at the train station, the reader authenticates and only valid pass/ticket holders are allowed to board the bus/train. The bus/train Conductors can also use an RFID validator to authenticate and validate the pass/ticket.

Library Management:  All the books in the library are tagged with RFID stickers and the users are issued with RFID library cards. When books are borrowed, the IDs of the books and the user’s card are linked.  The due date is written into the tag on the book and in the users card. When the books are returned, these are scanned by a RFID reader and checked with the corresponding due dates and the users card.

Animal Identification:  The cattle are tagged with RFID tags that has all the data relating to that particular animal. This data includes the name of the owner, date of birth of the animal, date of check/consultation with the VET, details related to health problems, etc. This helps in suitably identifying and tracking cattle.

Warehouse Management: All the items in a warehouse are tagged with RFID tags. Fixed and Handheld readers are used to track and monitor goods coming in and leaving the warehouse. Inventory taking is easy as all items can be checked against the availability in the warehouse (as per the System) and variances can be highlighted.

Shipment Tracking:  All shipments out of a manufacturing unit/warehouse are tagged with a RFID tag. Fixed and mobile readers are used to track the items till their destination. Various reports can be generated from the information gathered by the tracking system.

Supply Chain Management: Where tagging is feasible especially for high value items like jewellery, the entire supply chain from the receipt of raw materials, shipment of finished goods, to delivery to the end customer, can be easily tracked and monitored.  This prevents leakages or pilferage in the entire supply chain.

Retail Management: Large retailers like Walmart, Tesco, Best Buy, Metro, Circuit City, and others have already mandated RFID and want all their suppliers to be RFID enabled in two years. The major savings are in ‘Non Stock-Outs’ for all the products especially during weekends. Since it is very easy to track the inventory, replenishments can be programmed and stock-outs can be avoided.

Document/File Tracking: Important files/documents can be tagged with non-peelable tags. Having encrypted data written on these tags that can also be password protected can provide high security. Locating and tracking is easy through fixed and mobile readers.

Anti Counterfeiting:  High denomination currency can be RFID tagged to prevent counterfeiting, as duplicating these tags is extremely difficult since the security can be built into the tags.

Airline Baggage Tracking: RFID tags are used to tag baggage at airports. As the reading accuracy of RFID is nearly 99% compared to barcodes at 64%. Airlines will save the compensation amount they pay passengers for lost luggage and also gain the loyalty of customers.

Vehicle Immobilizers:  The vehicle keys are embedded with an RFID tag and the reader is placed behind the ignition block. On inserting a key into the lock it is authenticated by the reader and only the right key can start the vehicle. This key will then act as the focal point for the Customer Loyalty Program.

Customer Service:  Vehicles can be tagged with RFID tags that contain information on specific parameters of the vehicle. For example: last servicing done, miles covered, owners name, and other relevant information. When a vehicle is brought to the service station, it becomes very convenient for the service station attendant to take the vehicle for servicing. New data can then be entered into the tag after the completion of the service. Stolen vehicles can also be tracked, as all the information pertaining to the vehicle is available.

Health Care/Pharmaceuticals:  Vials of costly medicine are tagged with RFID tags and tracked at different points from the manufacturer to the retail store. Adulterating with spurious, non-conforming or duplicate drugs can easily be tracked and prevented, thus saving lives and protecting the manufacturer from legal issues.

Secure Payments: RFID Cards with adequate protection can function as an e-purse or charge card. These cards can be used to make payments for goods and services.

Potential Uses

RFID technology has good potential in:

Replacing Barcodes: RFID tags are often envisioned as a replacement for UPC or EAN  barcodes, having a number of important advantages over the older barcode technology. They may never completely replace barcodes, due to their higher cost.

Although both are Auto ID technologies, there are marked differences between the two as described in the table below:

Bar Code tags	RFID tags
Require ‘line of sight’ to read	Can be read without ‘line of sight’
Individually read	Multiple tags can be read simultaneously
Cannot be used if damaged or dirty	Can cope with harsh and dirty environments
Must be visible to be logged	Can be logged even if concealed
Identify only the type of an item	Can identify the specific item
Provides limited information	Provides greater amount of information
Information cannot be updated	Information can be overwritten repeatedly
Must be manually tracked for identification	Can be automatically tracked

Telemetry: Active RFID tags also have the potential to function as low-cost remote sensors that broadcast telemetry back to a base station. Applications of tagometry data could include sensing of road conditions by implanted beacons, weather reports, and noise level monitoring.

RFID Regulations & Standards

There is no global body that governs the frequencies used for RFID. In principle, every country can set its own rules for this.
Low Frequency (125 – 134.2 kHz and 140 – 148.5 kHz) and High Frequency (13.56 MHz) can be used globally without a license. Ultra High Frequency (868 MHz – 928 MHz) cannot be used globally as there is no single global standard. These frequencies are known as the Industrial Scientific and Medical (ISM) bands.

Some standards that have been set for RFID technology include:

Standard	Description
ISO 14223/1	RFID  for animals, advanced transponders
ISO 14443	Standard for very popular HF (13.56 MHz), used for RFID enabled passports
ISO 15693	Standard for HF (13.56 MHz), used for contact smart payment and credit cards.
ISO 18000-7	New UHF (433 MHz) industry standard for active RFID.
ISO 18000-6	Standard for UHF RFID.
EPC global	Standards for electronic product code.

EPC Gen2
EPC Gen2 is short for EPC global UHF Class I Generation 2. EPC global is a joint venture between GSI and GSI US working on international standards for use of mostly passive RFID and the EPC in the identification of many items in the supply chain for companies worldwide.