“To understand interference issues in RFID, one must know about RF frequencies, how they transmit and get absorbed and reflected around metals and liquids. UHF RFID is highly susceptible to interference in comparison to LF RFID system.”
While Radio Frequency Identification is a booming technology, growing at a rapid pace across industries with a CAGR of 11.8% over 2024-2032, there’s more to it than meets the eye. If you’re, as a business owner, looking to invest in RFID technology to bring automation to your workplace, automate various business processes, and enhance process optimization, it is better to have complete information. RFID has become increasingly popular in various industries due to its ability to automate data capture and improve operational efficiency and naturally businesses are inclined to implement this technology for better inventory control, automation, and efficiency.
Since RFID is a technology that uses radio waves to identify and track objects, providing assets with a unique digital ID through RFID tagging, understanding how RFID is categorized based on the frequency spectrum and how RFID tags, readers, and antennas communicate using RF signals is crucial. Like any wireless technology, RFID systems are susceptible to interference, particularly when operating at different frequencies and in the presence of metals and liquids. Many people are only aware of the fact that interference is an issue but they don’t seem to know why and how to resolve the interference issues or what kind of RFID system would fit their needs while keeping the interference and reader collisions at the lower end.
So, let’s explore the various interference issues in RFID, understanding the impact of low frequency (LF), high frequency (HF), and ultra-high frequency (UHF) on interference, as well as the challenges posed by metals and liquids.
RFID Frequency Bands: LF, HF, and UHF RFID System
In the entire frequency spectrum, RFID only operates within three different frequency bands, including LF (125 kHz, range 30 kHz-300 kHz), HF (13.56 MHz), and UHF (860-960 MHz). Each frequency band has unique characteristics that impact RFID performance and susceptibility to interference. This is where it gets interesting as understanding how these frequency bands work and how Radio Frequency (RF) signals transmit and carry data from RFID tags to RFID antennas and RFID readers is crucial and helps you make better decisions in choosing the best RFID solution for your business.
LF RFID System and RFID Interference
LF RFID systems are known for their ability to penetrate materials such as water and metal, making them suitable for applications requiring close proximity reading. The Low Frequency of the RF signals means that these RF signals have longer wavelengths. It allows them to penetrate thin metal layers and perform well in high metal or liquid environments. However, LF RFID systems are more susceptible to interference from other LF devices and electrical noise.
The RFID LF systems offer a short read range of up to 10 cm and low read rates.
HF RFID System and RFID Interference
HF RFID operates at a higher frequency (HF, 13.56 MHz) and is commonly used for access control, ticketing, and payment systems. HF systems are less affected by interference from metals and liquids compared to UHF, but they may still experience disruptions in densely populated areas with multiple HF devices operating simultaneously. The HF RFID system offers a read range of up to 100cm.
UHF RFID System and RFID Interference
UHF RFID offers long-range reading capabilities, going up to 15m, and is widely used in supply chain management, inventory tracking retail, and healthcare applications. However, UHF RFID is highly sensitive to interference from metals and liquids due to the nature of UHF radio waves, which are absorbed and reflected by such materials, leading to signal degradation and reduced read range. The ultra-high frequency range and shorter wavelength mean that these waves are unable to penetrate metal layers and perform poorly in metal and liquid environments.
Impact of Metals on RFID
Metals pose a significant challenge to RFID systems due to their ability to reflect and absorb radio waves. When an RFID tag is placed on a metal surface, the metal acts as an antenna, interfering with the tag's ability to transmit and receive signals. Known as detuning, this causes reduced read ranges and unreliable data capture, especially in UHF RFID systems.
To mitigate metal interference, specialized Mount-on Metal RFID tags (or Anti-metal RFID tags) and readers (with anti-metal features) are used, along with proper tag placement and orientation to minimize the effects of metal surfaces.
The antenna in UHF Anti-metal tags is specially designed and the tag is fabricated with a thick substrate such as foam to prevent detuning and reduce interference around metals and liquids.
Effect of Liquids on RFID
Radio Frequency Interference (RFI) is also caused in liquid settings. Liquids, particularly water-based substances, highly impact RFID performance in UHF RFID systems. Water molecules absorb UHF radio waves with shorter wavelengths, leading to signal attenuation and reduced read range.
In applications where RFID tags are required to be read through liquid containers or in humid environments, such as pharmaceutical and chemical industries, careful consideration of tag placement and selection of suitable RFID tags is essential to mitigate the effects of liquid interference.
RFI, apart from metal and liquid components at the premises, is also caused due to natural outdoor elements such as thunderstorms and static electricity, as well as man-made causes including radiation from network antennas, cabling, and overlapping RF frequencies coming from multiple RFID devices. RFID Reader collision is also a sort of interference issue when multiple readers are in use. Dense Reader Mode (DRM) in RFID Readers can solve such reader collision issues.
To conclude, before we select which RFID system is best suited to our business needs, understanding interference issues in RFID is crucial for implementing successful RFID deployments in various environments. Frequency bands, such as LF, HF, and UHF, play a significant role in determining the susceptibility of RFID systems to interference, while the presence of metals and liquids further complicates RFID operations. Through proper system design, tag selection, and environmental considerations, one can address these interference challenges and can get the benefits of accurate and automated data capture across diverse industrial applications. UHF RFID system, even though it is highly susceptible to RFI, offers a better read rate, longer read range and high performance.
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