How Does RFID Work

RFID (Radio Frequency Identification) is a revolutionary technology being rapidly adopted worldwide for a wide variety of purposes including inventory management. In this article you will find an explanation of the working of RFID in a nutshell.
With mass production of goods in modern industries and opening of retail chains all over the world, logistical management became increasingly difficult and the need for an automated labeling mechanism was felt, which could simplify inventory management. With bar code technology, that need was satisfied, but it is now rapidly being replaced by RFID (Radio Frequency Identification) technology, which can do the same job faster.

It's an implementation of wireless communication, with wider applicability, that has been rapidly adopted as an effective substitute for bar code technology all over the world. You might have already seen RFID in action while shopping in retail stores like Walmart, where it is used to label almost every sold product.

With roots in espionage technologies developed during the second world war, RFID technology has been evolving for many decades, while finding widespread acceptance only recently. The information about any product with an embedded RFID tag can be registered and stored in a database, through scanning of the object by an RFID reader. Most importantly, unlike bar code readers, there is no need for the product to be placed in line of sight for reading information. As long as the product is within the radio reception range of the reader, the encoded information in the tag can be easily read. More than one products can be scanned using RFID readers simultaneously. Let us see what is the underlying mechanism which makes this easy reading of RFID tags possible.

How Does RFID Technology Work?

RFID is an intelligent application of radio communication technology. Every RFID tag embedded in a product contains an integrated circuit chip (illustrate in the accompanying picture), with memory, which can be used to store information about a product, along with a transponder mechanism, which can transmit this information over a radio carrier wave after encoding and modulating it.

An RFID tag can either be active or passive. When the tag is powered by a battery to transmit data, it's known as an active tag. Passive tags don't have on board power to transmit data. They borrow energy from the scanner antenna in the RFID reader to transmit data. An RFID reader consists of a scanning antenna which can receive signals from the tags, decode them and process them for storing it in a database. Here is how a typical RFID tag reading occurs.

Step 1: RFID Antenna Sends Scanning Signal
An RFID tagged product may either be passed through a reader or scanner or brought into the vicinity of one. Line of sight identification is not necessary in case of RFID technology and the tags are embedded inside a product. The tag reading process begins with the RFID antenna sending a scanning signal which activates the transponder in a tag to respond. The scanning frequency is chosen to match with the transmitting frequency of the transponder.

Step 2: RFID Tag Transmits Signal
As soon as the active or passive RFID transponder receives the scanning signal, it sends out its own encoded and modulated signal over a radio carrier wave. Active RFID tags can transmit signals over long distances.

Step 3: Tag Signal is Received, Decoded and Stored
This transmitted signal is received by the reader through its tuned antenna. Subsequently, the signal is demodulated and decoded to register product information in a database. These RFID scanners are attached to computers where this information is stored.

Bulk identification of products and short scanning time are two of the prime advantages of using RFID tags, instead of bar code labels. RFID tags find varied applications. They have been used to track dwindling populations of animals in the wild. Employee ID cards have built in RFID tags, encased in plastic layers that are used in most corporate and industrial settings nowadays. The US army is one of the biggest patrons of this technology, using it to tag all containers transported worldwide, followed by Walmart which uses the technology in all its retail outlets. RFID chip implants in humans have been used for providing medical history and identification purposes.