One of the most efficient technologies gaining traction over the past few years, popular for asset tracking and item level tagging is Radio Frequency Identification (RFID). Though RFID has been around since WW2 when British forces used it to identify allied aircraft from enemy ones, its commercial use didn’t gain traction until the early 21st century with IoT development. Later on, RFID and machine-to-machine (M2M) communication became the basis for the Internet of Things (IoT).
When it comes to wireless technologies such as RFID, Wi-Fi, Bluetooth, and NFC, the range is quite important. In fact the ability to transfer energy, as in the case of RFID tags and Readers, it was Tesla whose experiments took precedents in radio communication and Marconi's (a few years later) first experiments sought to transmit energy over a 2m distance with the help of magnetic field coupling (near field). In fact, Marconi used some of Tesla's patented theories for his experiments, which Tesla allowed.
At present, RFID tags and readers are available in various read ranges and frequency ranges from leading RFID reader manufacturers and RFID Tag Manufacturers like Zebra Technologies, Impinj, EnCstore, Alien Technology and others. For example, the Zebra FX9600 Fixed RFID Reader operates on Ultra High Frequency (UHF) and the Zebra MC3330xR Handheld Integrated UHF RFID Reader offers read range up to 6m. Depending upon the use case, we need to choose the right RFID tag and reader for a cost-effective solution to our problem. Before talking about read range and use cases, let’s see how RFID technology works first.
Radio Frequency Identification
Radio Frequency Identification is a wireless technology that uses radio waves to transmit RF signals (thus energy and data) to communicate between an RFID tag and an RFID reader. When in use, an RFID tag is encoded with certain information and attached to specific items we need to identify and track. Whenever the RFID tag is in the range of an RFID reader (configured for the tag), it can catch the interrogating signal coming from the reader and send back the encoded data in the form of an RF signal for the end user.
An RFID reader is actually made of an antenna and decoder and transceiver, which is designed as a handheld or a fixed reader. The RFID tag also contains an antenna and a chip.
RFID technology has revolutionized asset tracking and inventory management as well as the supply chain industry. One of the key considerations when choosing an RFID solution is the read range, which is the maximum distance between the RFID reader and the RFID tag for successful communication.
Let’s explore some factors to consider when choosing an RFID solution for various use cases:
RFID Reader Antenna Gain
The antenna gain of an RFID reader is an important factor in determining the RFID read range. Higher gain antennas provide a wider beam angle and improved read range and for long-range applications, directional antennas should be considered.
RFID antennas are build in different shapes and sizes and can be mounted at a door to receive tag data from objects and individuals walking from the entry point as well as can be fixed on a toll entry point, as we use in FASTag application for toll collection.
Operating Frequency
RFID systems operate at different frequencies, each with its own advantages and disadvantages. Low-frequency (LF,125KHz) tags have a shorter read range (few inches) but are less prone to interference from metal and water while High-frequency (HF, 13.56 MHz) tags have a longer read range (10cm-1m) but are more susceptible to interference. Ultra-high frequency (UHF, 860-960MHz) tags have the longest read range (up to 12m) and are ideal for asset tracking and inventory management in large industrial environments.
Active RFID tags are also available in the market, which provide a read range of up to 100m, but these are big in size and cost more.
Tag Type Used
The type of RFID tag you choose also affects the read range. Passive tags rely on the energy from the RFID reader for power, while active tags have built-in batteries that provide additional power and extend the read range. Battery-assisted passive (BAP) tags are a hybrid between passive and active tags and provide longer read range than passive tags.
Interference in RF Signals
Interference from metal, Plastic, skin, water, and others can significantly affect the read range of an RFID system. For example, in a warehouse or industrial setting with a lot of metal, a low-frequency RFID system may be a better choice to avoid interference as near-field magnetic coupling can outcome these interferences better than electromagnetic coupling (far field) in UHF RFID.
Classical RFID vs Chipless RFID read range
The concept of chipless RFID is gaining traction due to its functionality and cost factor. However, when it comes to read range, chip-less RFID provides less read range than RAIN RFID and is mostly used as a replacement for barcodes, for accurate and quick identification.
Use Cases: RFID uses and read range
It is also worth noting that different use cases may require different read ranges. In a library, HF tags may be sufficient for tracking books, while in a logistics warehouse, UHF tags may be necessary for tracking pallets and large containers.
Passive UHF RFID/RAIN RFID is the most used RFID when it comes to supply chain and retail businesses. Apart from that, RAIN RFID is also used in medical equipment tracking and access control in healthcare, education, security, and other industries.
To conclude, the read range of RFID depends upon the magnetic (LF, HF) and electromagnetic field coupling (UHF) and depending upon the use case and cost involved with the RFID tag, we should make our decision accordingly. It's worth noting that Chipless RFID acts as an excellent alternative to barcodes, and is readily accessible in the market. It can be used for mail, on packages, and various objects that we need to scan up close, like a barcode.
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