RFID technology: what it is, how it works and what it is for

What is RFID

RFID technology (Radio Frequency IDentification) is used for the identification and / or automatic storage of data relating to objects or animals. It is based on the storage capacity of certain electronic labels, called Tags (or transponders), of information regarding the object to which it is coupled. These tags respond to remote interrogation by devices called readers.

RFID technology was used for the first time in 1939, during the Second World War, and has been developed since the sixties as a derivation for civil purposes of the military radio frequency system of Identification friend or foe (a system invented in Great Britain that was used to identify planes and understand if they were friendly or enemy vehicles).

Over the years, the technology has developed and has been used in many sectors: industrial, automotive, medical, e-Government (see passports, identity cards, etc.), transport and other uses. Given its versatility, it is considered a general purpose technology (such as electricity and the wheel for example) and has a high level of "pervasiveness", that is, once a use case is found in a point of the supply chain, the application and benefits they propagate quickly upstream and downstream of it. Through the use of RFID it is possible to create, thanks to the development of information technologies and the internet, a system of interconnected objects that allow the collection and processing of data in a single large global network.

How it works

It is a radio frequency wireless communication system where the reader, once in the operating range, detects the tag and queries it, the latter responds by transmitting the data contained in the memory to the reader (usually information on the product on which it is applied). 

The aim is to obtain data which, once processed by management systems, are able to return information and analysis regarding traceability, inventory in the warehouse and business planning. In figure 1 opposite we can see an example of a tag with the indications of its components.

Components

RFID technology consists of four fundamental elements: TAG, Management System, Antennas and Readers. Without even one of these elements it is not possible to use this system.

  • TAG – small radio frequency device consisting of a chip, with memory, connected to an antenna and inserted in a container or incorporated into a paper or plastic label. Tags enable short range data transmission without physical and visual contact. With some exceptions, the data contained in the tag memory has a unique identification code.
  • Antenna – it is the conductive element that allows you to send and receive the data contained within the tag. The readers have antennas to emit radio waves. These waves are collected by the antenna contained in the RFID tag and used to power the microchip which releases information to be returned to the reader.
  • Reader – it is the element that in RFID systems allows you to access to the information contained in the tag. They can appear as fixed devices, in case they have to read, for example, large quantities of products at the entrance or exit of the warehouse, or mobile devices, have a shape similar to palmtops and allow warehouse employees to control certain quantities of selected goods. Antenna and readers can be combined in a single device or be two distinct devices.
  • Management system – information system that is connected to the network and to the readers. This system allows, starting from the identification codes coming from the tags, to obtain all the available information associated with the objects and to manage this information for the purposes of the use case.

RFID Tags

Also called RFID Transponder, it is the main element of the whole system as it allows you to read and write data contained therein. Tags can vary in shape, size, material and operating frequency but all of these can be grouped into three large families: Active, Passive and Semi-Passive or Semi-Active.

Active

This category includes those tags that receive energy from their own power supply to operate, usually made up of a long-lasting battery. They are capable of self-transmitting data to the reader and cover far greater distances than passive tags. They have large memory, are often rewritable and can contain sensors to take measurements, such as heat, temperature and pressure. They are usually designed for durable use.

Passive

They are tags that do not have their own energy source but receive it from the signal coming from the Reader. They consist of a chip (with unique identifier and possible memory), an antenna and a support or container. As the reader passes, the radio frequency activates the microchip inside the tag, providing the energy necessary to operate. This energy during the reading phase will be reused to respond to the reader by transmitting a signal with all the information stored inside of it; in the writing phase, however, it will allow you to save the data sent by the reader. The distances in which they can operate are of the order of a few meters or a few centimeters depending on the operating frequency.

Semi-passive

They are tags equipped with their own energy source which is used to power the microchip or other devices (such as sensors) but not to power the transmitter. To be able to transmit information, they must enter the range of the reader / antenna.

Types of passive Tags

Passive tags can be divided in Near-Field RFID and Far-Fiel RFID, depending on the frequency band used to communicate and the electromagnetic phenomenon.

Near-Field RFID

In the near-field region, the interaction between the components is dominated by the magnetic field generated by the antenna, which induces an electric current in the tag by inductive coupling and enables the chip to be activated. Tags of this type are part of the LF and HF classes.

Far-Field RFID

In the far-field region, the interaction of the components is dominated by the electromagnetic field created by the antenna. The RFID tag resonates with the frequency of the EM field and the current generated activates the chip. Tags of this type are part of the UHF class.

Operating frequencies of RFIDs

RFID tags can be further classified based on the frequency of the signal used for communication. These frequencies depend on the nature of the tags and the intended applications, are also regulated by international and national organizations. The most used frequency bands in RFID technology are the following:

LF Band

Acronym for Low Frequency, it is located in the lowest part of the RF spectrum, within the LF band there are two most used operating frequencies: 125 Khz or 135 Khz. It was the first to be used historically and still has a significant presence on the market today. Characterized by a very limited reading distance, it operates almost in contact, and given its characteristics it is ideal to be used for alarms, attendance or access control, traceability of pets and breeding, etc.

HF Band

Acronym for High Frequency, are frequencies that work at 13.56 Mhz, it is supported in the ISO 14443, ISO 15693 and NFC (Near Field Communication) standards. It is today the universal band, because it can be used all over the world. It can be used for identification and tracking, pallets, access control and other use cases that require a short reading distance (up to 1.20m).

UHF Band

Acronym for Ultra High Frequency, these are frequencies that work at 868 MHz or 915 MHz, normalized in the EPC reference standards. The use of this frequency may be restricted by the authorities of individual countries in terms of maximum power and frequency bands. In fact, the band is not assigned uniformly in the USA, Europe and Asia. Tags of this type have a greater reading distance than the others and are therefore mainly used for retail, logistics, warehouse management, etc.

The advantages of RFID technology

Using RFID allows you to eliminate the cost of errors. In fact, it allows to eliminate risk of losses, thefts and incorrect shipments.

It is used to have a more efficient warehouse management, the total traceability and identification of the product and trademark protection.

Advantages compared to the use of the Barcode

Barcodes have a function very similar to RFID technology and are therefore often chosen to perform common functions as an alternative to passive tag technology.

The latter represent a larger investment than the barcode for the customer, but undoubtedly offer greater benefits. Unlike the barcode, the Tag can also be rewritten and protected with certain passwords, thus making it a safer and more reliable tool.

These two technologies can still be used in combination, on the RFID tag it is in fact possible to print a barcode, this to simplify some steps of subjects who do not have a reader for example.

Reading skills

The barcode reader allows you to read one product code at a time, making operations such as warehouse loading, unloading and inventory long and expensive. The use of RFID in these cases allows you to read over a hundred products simultaneously.

Reading range

While the barcode reader has a reading range of a few centimeters, the RFID reader can read tags applied to products located up to ten meters away.

Reading speed

Even the reading speed of the RFID readers is surprising, it is in fact very fast (quantifiable in ms) unlike the barcode which is slower.

Possibility of reading through objects

Thanks to RFID it is also possible to identify the tags of objects even if they are contained, for example, inside boxes. The barcode reader, on the other hand, must visually identify the black-on-white code in order to read its content.

Unique identification

RFID tags have a unique identification code, each object to which it is affixed becomes in fact unique and identifiable, in this way it is possible to trace it along the entire supply chain. The barcode does not offer this possibility and usually products of the same type have the same barcode.

Use cases of RFID technology

RFID technology is very versatile, this is also demonstrated by the multiple applications and uses that are identified over time. In fact, over the years it has shown a strong adaptability to the different sectors in which it has been used, among these we find: