How Can I Achieve a 5-Meter Read Range?

By RFID Journal

  • TAGS
Ask The ExpertsHow Can I Achieve a 5-Meter Read Range?
RFID Journal Staff asked 4 years ago

I require a read range of 5 meters (16.4 feet), and the tags I have purchased are advertised as being able to achieve that range. However, when I trial them, they have a read range of only 0.5 meter to 1 meter (1.6 meters to 3.3 meters). Can you advise on how I can achieve the 5-meter range I need without compromising tag size?

—Christopher (United Kingdom)

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Christopher,

It appears you have purchased passive ultrahigh-frequency (UHF) RFID transponders, as other tags would not advertise a read range of 5 meters (15 feet). There are a few possible explanations for the difference in the advertised read range and the range you are experiencing.

The most likely is that the material on which you have placed the tags is detuning the antenna. When a tag is placed on material that conducts electricity, the material detunes the antenna so it cannot receive a signal at the appropriate frequency from the reader. This is like if you touch an AM radio antenna with a piece of metal; suddenly, instead of hearing a clear radio signal, you will hear noise. Additionally, your body is mostly composed of water, which conducts electricity, so if you are holding the tag between your thumb and forefinger, you are detuning the antenna.

Another possibility is that the tag is not oriented properly to the reader antenna. If you are using a linear-polarized antenna, energy is emitted in a narrow band going either north-south or east-west, depending on how you orient the antenna. If you have a dipole tag with the antenna pointed north-south and a linear-polarized reader antenna, the only part of the tag receiving energy will be where the vertical beam of energy crosses the horizontal antenna. Since the antenna is receiving very little energy, the read range will be very short.

Finally, it is possible that you purchased tags that utilize a different frequency than the one used in the United Kingdom, where you are based. If you bought tags that operate at 915 MHz (the frequency used in the United States) and readers that operate at the 865.6 to 867.6 MHz band (the U.K. frequency band), the tags will not perform optimally.

I hope the above helps you to identify the issue.

—Mark Roberti, Founder and Editor, RFID Journal

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