Understanding RFID Tag Distance Range

Before going into the specifics of the RFID tag range, you need to understand the basics of RFID technology. An RFID system consists of a tag, a tag reader, and a backend system.

The RFID tag attaches to the item that needs to be tracked and consists of an antenna and a microchip.

An RFID tag reader acts as the central ground for communication in the system. It emits radio signals, which the tag’s antenna receives and sends to the microchip. When it receives the signals, the microchip transmits data back to the reader. An RFID tag reader thus functions in a release-and-receive loop of signals and information.

Afterward, the software or backend system will interpret the data sent to the reader. This component relates to the database to store and use the collected information.

There are active, semi-active, and passive types of RFID tags.

• Active tags have their own batteries or power source. They release radio signals that the reader picks via antennas. This feature allows them to work for long distances and reduces the need for human interference. An alternate name for active tags is long distance RFID reader.
• Semi-active tags are the in-betweens of active and passive RFID tags. They use a battery to juice up the tag’s circuitry and receive the radio signal directly from the reader. Additionally, they are suitable for applications that require a long read range.
• Passive tags have no power source of their own. They depend on the energy from the signals emitted by the RFID reader to power the microchip. Therefore, passive tags should be within a certain distance from the reader for data transmission. In other words, they have a shorter read range than active and semi-active tags. But unlike long-distance RFID readers, passive tags have lower chances of radio interference.

Read range is the term that describes the distance from which a tag is read. However, the read range of an RFID tag is more than just a specification. It is a vital factor that determines how effective your tag will be.

For instance, a long-distance RFID reader allows you to track all your tags automatically. It eliminates the need for manual scanning or precise positioning. The resulting advantage of this is faster data collection and proper time management. Long-distance RFID tags also help to reduce labor costs and ensure a smooth workflow.

An RFID tag with optimal read range ensures that your tag remains reliable in different environments. However, certain factors could affect your RFID tracking distance. These include;

There are three radio frequency bands in RFID technology. RFID systems operate at frequencies that range from low to high and ultra-high. In RFID tags, the higher the frequency, the longer the read range.

Low-frequency RFID systems operate within small spaces. They require the tag and reader to be at most a foot or half a meter apart. This occurrence is termed the near-field effect. While low-frequency RFID tags are unsuitable for long-distance tracking, they are perfect for many applications. An example is card readers and key cards, where the tag is brought close to the reader.

When a low-frequency tag is out of range, the intensity of the radio frequencies it receives drops rapidly.  If the distance increases between the tag and the reader, the power sent to the tag drops. Even though high-frequency RFID tags offer a wide read range, they are more liable to interferences. The read range of HF RFID tags makes it easier for objects to obstruct the transmission between the reader and the tag.

RFID tags are grouped into passive and active. Passive tags don’t have a power source. Instead, they rely on the energy from the reader’s signal to power the microchip and retrieve information. This reliance limits the read range of passive tags to a few meters. In other words, to properly function, the tag and reader must be in proximity. In contrast, active tags have batteries that help them transmit data hundreds of meters away from the reader.

RFID tags work both inside and outdoors. These tiny devices are versatile in their applications. You can find them both in the fields where livestock graze and in the organized haven of a shopping mall. Alas, this versatility means that RFID tags will often encounter substances that can impact their read range. Examples include water and metals that can absorb and reflect radio signals.

Both the tag and the reader have antennas. The design of an antenna plays a vital role in determining read range. Since antennas with a narrow focus read longer than a simple whip antenna, you may want to take a shortcut. While it is easy to increase your read range with a high-direction antenna, doing this causes more problems.

A narrow beam causes interference with the signals of any other receiver in the direction of your beam. Any low-frequency RFID tag along this path will face interference. The main result of this will be inaccurate data collection.

The shortest read range of an RFID tag is about 10 cm. The tags with this range are low-frequency (LF) RFID tags. They operate within 30 to 300 kHz frequencies and have a slow read time. However, regarding interference, LF RFID tags have the least occurrence.

High-frequency (HF) RFID tags have a read distance of 10 cm to 1m. They function at frequencies between 3 to 300MHz, although many HF tags operate at 13.56MHz.

Ultra-high frequency (UHF) RFID tags have the longest read range. In a passive tag, the tracking distance can reach 12 meters. On the other hand, with active tags, a UHF RFID easily achieves 300 feet or 100 meters.