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02 Dec 2021 | 09:00

What is RFID and how does it work? A short guide for all sectors


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How does RFID work?

Radio frequency identification (RFID) was developed in the 1940s, and after years of development and innovation it became widely used from the mid-1990s on. Now, we find RFID technology in all sorts of everyday items, from passports and ID cards to retail stock, but what is RFID and how does it work?

Essentially, RFID is a form of wireless communication that uses readers to track and identify data-encoded tags (sometimes called transponders). Each tag contains information about the item it is attached to and it broadcasts this to the reader, which may send it on to a host computer. In this way RFID works like a barcode, but RFID has two particularly useful characteristics;the reader does not need direct line of sight to read the tag, and RFID allows each item to be identified and accounted for as a unique unit.

It is now possible for RFID tag readings to be automatically copied from the reader to cloud-hosted software, from where they can be read and monitored from any location at any time. This allows the RFID-tagged items to become part of the Internet of Things (IoT) and can be extremely useful in applications like manufacturing, RFID asset tracking, and supply chains.

Types of RFID

RFID tags are often discussed in terms of two forms: passive tags (which do not have a battery and rely on electromagnetic waves) and active tags (which have an internal battery). Some hybrid versions are also available, such as battery-assisted passive systems.

Again speaking generally, active tags can be read from further away and constantly broadcast a signal, so they are ideal for continuous tracking. However, because they contain more hardware than passive tags, they tend to be bulkier. Passive tags are very affordable and can be very small, but they cannot actively broadcast; instead, they wait for a signal from an RFID reader, and then respond.

This overview simplifies things, however. It is more accurate to think about RFID systems and the benefits of RFID in terms of the frequency bands they use: low, high and ultra-high frequency. The radio waves that RFID systems use (and thus, the RFID systems themselves) behave differently according to frequency, and frequencies that are good for some applications are less good for others.

Low frequency RFID systems 

These cover frequencies from 30 KHz to 300 KHz, which provides a short read range (i.e. the reader must be close to the tag, usually within 10 cms or so) and relatively slow read speed. However, low frequency RFID systems resist interference from radio waves and are often used for access control.

High frequency RFID systems

These operate at between 3 and 30 MHz. They have a longer reading range (between 10 cm and 1 m) but are more sensitive than low frequency RFID to interference. High frequency systems are used for data transfer applications, including payments (for example, near-field communication [NFC] uses high frequencies for security).

Ultra-high frequency RFID systems

Ultra-high frequency RFID operates on frequencies between 300 MHz and 3 GHz, and ultra-high frequency RFID systems have faster data transfer and longer reading distances than other forms of RFID. Passive tags used with ultra-high frequency RFID can very affordable and most active RFID systems (i.e. those that use active tags) operate within the ultra-high frequency range. 

What can RFID do for me?

Because RFID tags can be read without line-of-sight connection, RFID readers can be easily incorporated into infrastructure such as shop and vehicle doors or fittings, which makes the constant monitoring of tagged items very easy. That is why alarms sound if you are on your way out of a shop and the cashier has left a tag in one of your items ─ the alarm is triggered by the RFID reader embedded in the door, which reads the RFID tag in the item as it passes.

Other uses of RFID technology include:

  • Stock management (in retail premises and warehouses)
  • RFID asset tracking
  • Crime prevention (such as the prevention of shoplifting or theft from work premises)
  • Identity verification in credit cards, travel passes. etc.
  • Security of people and data (e.g. RFID tags in ID badges and cards that may be used to access buildings or computer systems; passports; driving licences)
  • Asset protection (e.g. to monitor easily-lost items such as tools and equipment)
  • As part of a digitalised supply chain (as we have seen, when combined with cloud software, RFID-tagged items become part of the IoT and can be tracked accordingly from anywhere)
  • To ensure traceability/ensure an audit trail for goods and components 

What are the benefits of RFID?

There are too many to ignore! For example:

  • Hundreds of RFID tags can be read in seconds, and this process doesn’t require a direct line of sight. This can make processing times much faster, increasing productivity and saving money.
  • RFID tags provide real time inventory and warehouse data with less effort than other technologies and – when integrated with cloud software and the IoT – from any location. This makes them ideal for many Industry 4.0 applications, including supply chain and component tracing.
  • Because RFID tags are now small and cheap enough to be built into everyday items like credit cards, ID cards and badges, they can be used to automate processes such as access to buildings, events or services; passport control and retail payments. This saves time and money.
  • Some RFID tags are ruggedised and can be used in harsh conditions and with a range of substances including metals and liquids (which can be advantageous  in sectors like chemical manufacture, metallurgy and welding).
  • Most RFID systems are cost-effective and the savings they generate quickly cover the investment made (although this may take longer with specialised or complex systems).
  • RFID tracking provides better control of processes, which can be used to optimise production, increase revenues and enhance customer satisfaction.
  • The traceability and error-free nature of RFID data can be used to support regulatory compliance and documentation during audit.

What do I need to use RFID?

The basic components of an RFID system are the tags and readers and, if required, a cloud software system that can host the resulting data. Thereafter, things get a bit more complicated! Before choosing an RFID system you need to know:
  • Whether the readers need to be mobile (e.g., hand-held readers) or fixed (perhaps embedded in doors or fixtures, as in retail)
  • The frequency required in the tags (tags broadcast on different frequencies, and this affects the distances from which they can be read, among other things)
  • The type of tag required, i.e. passive vs. active vs. hybrid

It can be helpful to analyse all possible RFID uses within your organisation, assess likely costs then run a cost/benefit analysis. Some organisations begin with pilot studies, and for organisations that have begun their digital transformation this can help to show the benefits of integrating RFID data into their wider use of IoT and cloud technologies.

If this has been interesting, why not have a look at our RFID product offering, RFID asset tracking solutions, and/or get in touch to discuss your specific requirements?


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