HF or UHF – Which RFID Frequency to Use?

HF or UHF? Which RFID frequency do I use?From those who are new to the world of RFID and rugged handheld computing, one of the most common questions I hear is “Which RFID frequency should I use: HF or UHF?” In this post, I’d like to help make this decision process a little bit easier. There are lots of different applications that use both HF (high frequency) and UHF (ultra-high frequency) RFID. And, like most options we have to choose between, each frequency has different pros and cons, so it really depends on what’s important for your specific application.

Below, I’ve provided a kind of assessment that will hopefully help you decide which RFID frequency is most beneficial to your organization. Asking yourself these questions will help give you a better idea of which direction you might want to take. If you are trying to choose between HF and UHF, I would definitely recommend doing some extra research on this topic, but this is a great starting point that will help you quickly understand some of the differences between HF and UHF RFID technology. So here you go.

1) Do you need the ability to read and write data over a distance greater than ~50 cm?

Yes → UHF might be a better option, allowing you to transfer data over several meters, while HF can only transfer data up to about 50 cm.

No → HF might be better for you because its range is shorter, making it more reliable.

2) Will your RFID tags be placed near liquids, metals, carbon substances, or other dielectric and conducting objects?

Yes → HF would probably work better because it is less vulnerable to interferences from surroundings. However, there are some manufacturers that have designed UHF tags that will work in these environments as well.

No → HF and UHF would both work well.

3) Do you need to store more than ~110 bytes of data on your RFID tags?

Yes → HF would probably be better because these tags can store between 64 bytes and 8 kilobytes of data, while UHF tags can only store 24-110 bytes of data.

No → Both HF and UHF would work—at this point you’d probably want to choose the most cost-effective option.

4) Do you need to read more than 20 RFID tags at one time?

Yes → UHF might be better for you since it can read up to 200 tags at a time, whereas HF can only read up to 20 tags at a time.

No → Both HF and UHF would work. However, if you’re planning to narrow down on one tag at a time, HF would probably be better since UHF might pick up multiple readings.

5) Will your tags be located in an area with a high amount of Electromagnetic Interference (EMI)? EMI is emitted by motors, robots on assembly lines, conveyors with nylon belts, etc.

Yes → HF would probably be best because it is less susceptible to inaccuracies due to EMI.

No → HF and UHF would both work.

6) Does your application require faster data transfer?

Yes → UHF would probably be better because it transfers data faster than HF.

No → HF and UHF would both work.

7) Is power usage an important consideration for your application?

Yes → HF might be better because it uses less power than UHF.

No → HF and UHF would both work.

8) Are there inhibiting UHF restrictions in your geographic location that would interfere with your use of UHF RFID?

Yes → HF might be better because the same HF technology is accepted worldwide, whereas UHF restrictions vary according to region.

No → HF and UHF would both be fine.

Also, another FYI: some RFID readers don’t support certain frequencies, so be sure to consider that as well. Hopefully this helped! You may have heard that we now carry RFID readers for our rugged handheld computers, which operate at both HF and UHF. Feel free to contact us to find out more.

If you have any other questions about RFID frequencies, ask away in the comments below.

 

Source: TURCK

 

 

 

 

23 Comments

  1. What a great article! Short and straight to the point, no technical BS which makes my head spin when I’m just starting the research on HF vs UHF. Thank you!

  2. Thank you for your assessment.

  3. Thanks Josh!
    I just wonder why the UHF range is greater than the HF (requirement 1/), while the free space losses increase with frequency.

    • Hi Bendel,

      If I understood your question correctly: You asked, “Why is the UHF read range greater than that of HF?” Correct? It is more efficient to transmit power at a longer distance at a higher frequency in free space, therefore, antenna size, and power requirements are less to do so. Thus shorter antennas can be used with a higher frequency such as UHF. Higher frequencies also allow a wider band for modulating signals allowing one to obtain a higher frequency transmission (speed). All of this is important when dealing with applications that are in a mobile computing form factor where size, range, battery power, and speed come into the application’s needs. Keep in mind, however, that higher frequencies such as UHF are more susceptible to reflection on walls or other objects/barriers causing potential communication issues, that is where HF or LF RFID frequencies may be better suited for applications needing to do so, however, I have seen a trend in the RFID industry that is optimizing antenna designs and tags to account for this issue seen at higher frequencies. Hope this helps answer your question.

      Josh

      • Thanks a lot Josh. Yes you understand well my question.
        If i understand well, it’s a compromise between power radiated by the antenna (increasing with frequency) and the free space losses, also increasing with frequency (Friis transmission equation).
        I have read that LF and HF RFID use magnetic coupling (i.e. as a transformer, no radiation) while UHF uses propagation (radiation). Is it true that UHF RFID doesn’t work with closed tag (no radiation zone)? Why?
        thanks a lot

        • Hi Bendel. You are correct, LF and HF typically rely on inductive coupling using a magnetic field in order to receive power and transmit a signal. In order to do so, the LF and HF tags uses an inductive coil-like design that requires conductive material to get it to function. This is typically called “Near Field” communications or NFC technology. UHF Gen 2 is different in that it uses far field radiation (just as you mentioned) to read a tag and do it a higher efficiency and speed (approx. 60 times more efficient than HF). I have seen UHF being used in NFC applications as well however (and it technically could be designed as a magnetic coupler, I just haven’t seen it used this way very often). IDBlue has a UHF reader that works in close range and there are other readers out there that are “NFC” like as well. Again, there are advantages with each frequency (LF, HF, UHF) but it seems that the best advantage typically lies within what each industry uses in their infrastructure today. If an industry is already using LF, it becomes more problematic to get them to convert to a different frequency even if there are bigger advantages with that different frequency because their existing infrastructure and capital may have already been tied up with that technology which was chosen years before. Hope this helps.

          Regards,

          Josh

          • Thanks a lot Josh.
            Best regards

          • Hello Josh!
            A question related to the new iso 18000-3 mode 3 standard:
            I have been told that mode 1 is not compatible with stackable tags, because it uses tuned tags. And the new standard mode 3 is compatible with stackable tags because the tags are untuned.
            I don’t see why it is not possible to use untuned tag with mode 1 and the opposite with mode 3. For me it is uncoupled, it s only a matter of read range improvement that deals with tag but not on a particular standard. Have you heard something about that?
            Thanks Josh

  4. Burak Onal says:

    Hi,

    Great article. I wonder if there is any readers in the market whose frequency level can be changed and become UHF, HF and LF. I need the flexibility because I will conduct experiment to find the best option.

    Does UHF reader read HF and LF tags as well?

    Thank you!

  5. Burak Onal says:

    Hi,

    Thanks for the great article. Please ignore the message above and answer this!

    I wonder if there is any readers in the market whose frequency level can be changed and become UHF, HF and LF. I need the flexibility because I will conduct experiment to find the best option.

    Does UHF reader read HF and LF tags as well?

    Thank you!

  6. Thanks for information.
    I need to know about the security for both HF and UHF RFID tag. Are they have same privacy?

  7. Thank you for such helpful information!

  8. Krishna Kumar says:

    Hi,

    Thanks for the article.

    Which is better for School Library management system?

  9. Marcelo Uzeda says:

    A great article, right to the point. In simple questions can drive us in the better way.

    Congrats.

  10. Thanks for sharing. It’s very useful.I don’t konw which tag I should buy before,
    now I know that I should buy UHF tag on http://www.asiarfid.com

  11. great share. useful. get your explain to may client that easy for them to understand.

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  13. We provide many sorts of UHF Metal Tags for vehicle,container tracking,asset tracking,stock management and application in other fields.

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