RFID: A technology dating back to World War II

Johannesburg, 16 May 2024
Stef du Plessis, Director, Osiris.
Stef du Plessis, Director, Osiris.

To understand why RFID (radio frequency identification) installations sometimes fail or don’t perform as expected, it’s important to understand the technology itself. We asked Stef du Plessis, a director at Osiris, to provide an overview of RFID technology and its widespread use across various industries. Osiris Technical Systems has been implementing RFID solutions for almost 40 years, across industries as diverse as agriculture, mining, retail, fleet management and hazardous materials storage and transportation.

He starts out by explaining: “RFID has been around for a long time – it was initially deployed during the Second World War to identify friend or foe using radar. Since then, it’s evolved into a widely used technology in retail, logistics, warehouse management and even industrial applications.”

Arguably the most well-known example of RFID implementation in retail is from Walmart in the USA, whose deployment of RFID spurred other retailers to adopt the technology. RFID requires as a minimum a tag, a reader and a system to make sense of the data.

RFID allows reading of a tag at a distance. For most RFID systems, the tags are passive, which means they have no power source but are powered by radio frequency field generated by the reader. The tags are designed and made to respond in a specific way when powered up by the RF field of the reader. The reader then decodes the tag information and passes it on to an IT solution. Du Plessis explains: “A typical broad category would be passive tags, which don’t have their own battery; they just react when in the field of the reader. In general, passive tags operate within three main frequencies: low frequency, high frequency and ultra-high frequency.”

Low frequency has been around a long time and is primarily used for access control and animal tracking. The reading range is between one and two metres. High frequency is also fairly common, used for near-field communication (NFC) tags. Applications include access control, bank cards, etc. Here the reading range is between two and 10 centimetres. Ultra-high frequency (UHF) is specifically designed to speed up logistics and make sure it works better. The big advantage with UHF is that you can power up and read a tag from a long distance of up to 20 metres, detecting multiple tags inside a box or reading a shelf stacked with clothing.

The speed at which you can read UHF tags, and the fact that they can be read at a longer range, makes them easy to use. However, these qualities offer both challenges and opportunities for users. He explains: “As a vehicle approaches a tollgate bearing a toll tag using UHF, it can be read at speed. Between 700 and 1 200 tags can be read per second, and the reader continues reading tags until they are out of the field. This is ideal for logistics and warehouse management. You can build a portal that vehicles pass through with tagged items, and you can read those tags on the fly.”

The parts of an RFID system.
The parts of an RFID system.

A tag is a silicon chip attached to an antenna – typically an aluminium printed antenna. The reader also has an antenna, and as the tag moves through the reading range, it gets power from the RF field and transmits information. Tags are traditionally designed to work in either Europe or the US, where the frequencies differ, but South Africa is able to use both frequency ranges.

Each tag has a unique ID and an electronic product code (EPC) that is typically programmed according to the requirements. This identifies the tag and the item to which it is attached. Some tags have additional user memory that can be programmed by the manufacturer for warranty or maintenance purposes, or just to record information about the tagged item. Finally, there’s a part of the memory used for access codes or passwords required to rewrite the technology or access the memory.

Each tag has a unique ID.
Each tag has a unique ID.

In line with the tags, readers have become more sophisticated with time and able to scan tags from greater distances. Readers can be handheld or fixed. A handheld reader can be used to scan items individually in a warehouse, or used to manually check everything inside a truck, ensuring that the order is correct. However, as mentioned earlier, it’s also possible to install a fixed reader to create a portal that reads everything inside the vehicle as it passes through.

Fixed readers range from a ‘dumb’ reader that requires a PC to more sophisticated ones that run their own software and send information to whatever backend you use.

Then there are desktop readers that read one tag at a time, such as those used at retail checkouts. You also get ones that can read bar codes and RFID at the same time.

“The key thing here,” says Du Plessis, “is to ensure that you have the right tags for the application, the right reader for those tags, the right antenna in the right place for your frequency and the correct frequency that works with everything else. And to do that, it’s advisable to partner with a business that has experience in RFID installations and that can advise you on which technologies will work best for your specific requirements.”