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Understanding RFID and RFID Operating Ranges

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Use of RFID in Industry

Radio-frequency identification (RFID) has an enormous variety of uses, ranging from public transportation to animal identification to product tracking. In industrial environments, RFID tags are used to track parts or assets, useful for automation and/or logistics purposes.

Three frequency groups make up virtually all RFID tags: low frequency (LF), high frequency (HF), and ultra high frequency (UHF). Each frequency group has their own typical uses because of their inherent advantages.

Types of RFID Tags

There are three types of RFID tags: Active, Semi-Active (or Battery-Assisted Passive) and Passive. Active tags are tags that consistently emit radio signals in order to be picked up by a reader. These tags are accompanied by a battery or an other continuous power source, and an antenna to transmit and receive radio signals. Depending on the size, active tags can hold various amounts of data, typically not more than a few thousand bytes. Data can be both written on or received from an active RFID tag for purposes such as logging or documentation.

Semi-Active tags, or Battery-Assisted Passive tags (BAP), use a battery to power the tag’s integrated circuitry without sending signals, while the signal power comes directly from the RFID reader. Both active and semi-active RFID tags operate over longer ranges than passive tags.

Passive tags are powered solely by the reader’s magnetic field emissions, which induce a current in a passive tag’s antenna. In turn, active and semi-active tags cost more, making them only ideal for higher-value assets.

Low Frequency RFID

Low Frequency RFID has the shortest read distance, about 10 centimeters between the reader and the tag. The read time is also slower, however, the low frequency has the least amount of radio interference. Low frequency covers ranges from 30 to 300 KHz. Low frequency is also not considered globally compatible due to differing frequency and power levels worldwide. Common uses for LF RFID include animal tracking and access control.

High Frequency RFID

High Frequency RFID is very common, and operates in a frequency range from 3 to 30 MHz. The read distance ranges from 10 centimeters to 1 meter. The majority of HF RFID devices function at 13.56 MHz, with moderate radio interference sensitivity.

Several uses of HF RFID involve Near Field Communication (NFC), which focuses around data transfer between two devices. This is often seen in smart payment cards and other proximity-activated devices. Other industries that use HF RFID for payment, cataloging, and/or tracking purposes include marketing, waste management, automation, health and medical, and manufacturing

HF RFID tags can come in many shapes and sizes to suit numerous specific purposes. They can accommodate read-only, write-only, and rewritable RFID tags. Ranging memory capacity from 64 bytes to 8 KB, readers can handle up to 20 HF tags at one time.

Ultra-High Frequency RFID

Ultra-High Frequency RFID tags have the fastest reading speed and the longest read range. While near-range UHF tags are an option, compared to HF tags, near-range UHF tags have a shorter and narrower read range. However, near-range UHF tags are less susceptible to interference, providing a performance advantage.

Far-range UHF RFID tags can read at ranges as far as 12 meters with a passive RFID tag, whereas active tags can achieve ranges of 100 meters or more. The operating frequency of UHF RFID tags ranges from 300 MHz to 3 GHz, and UHF tags are the most vulnerable to interference. To counteract signal interference, UHF tag producers often manufacture readers and antennas that maintain reliability in troublesome environments.

UHF tags are cheaper to make than HF tags (~5-15¢ labels compared to 50¢-$2) , causing them to appear in a wide variety of applications including inventory management, anti-theft management, and wireless device configuration.

RFID technology is a growing market, and UHF tags are becoming increasingly popular due to their lower cost and equivalent effectiveness to LF and HF tags. If you are searching for a new tagging or tracking system that will improve your business model, RFID may be a valuable option to consider.

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