RFID – Differences between HF and UHF modes

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From those who are new to the world of RFID and rugged handheld computing, one of the most common questions you could hear is “Which RFID frequency should I use: HF or UHF?”

In this article, we will 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.

RFID - Differences between HF and UHF modes

RFID - Differences between HF and UHF modes


Up until now HF Tags have been viewed as a more reliable and proven technology. However recent developments established that UHF tags are equally as reliable and often times can offer better performance across many applications. 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.

The "Old" HF Vs. the "New" UHF

HF Tags are considered more “mature” tags, since they have been around for longer. While UHF tags are dominant technology for supply chain applications, it is believed that due to their “maturity” and a short read range HF tags are a better choice for item level or near-field applications.

However over the past years it has become apparent that UHF Tags are equally as reliable as HF tags and often can offer better performance. UHF tags do not need to be near field tags to be read at a close range. Unlike HF tags, UHF tags can be read both at close and long ranges.

Misconceptions about UHF Tags

While UHF tags can obviously offer a versatile read distance, many believe there are drawbacks to UHF Tags. For a long time it was believed that:

1. UHF Tags could not function on/in water or metal;

2. UHF Tags could not provide shorter read range;

3. UHF Tags are too large and are inappropriate for applications where a smaller footprint is necessary;

1. UHF Tags cannot function on or in liquids or metals.

It is well proven that HF tags perform reliably and accurately on liquids and metals. However, for a while it was believed that UHF tags cannot function on/in liquids. The later claim is untrue: UHF tags perform equally well (if not better) on both liquids and metals. UHF Gen 2 Tags not only work on liquids they actually work in containers that are filled with liquids. In 2009 an RFID tag manufacturer demonstrated that a UHF Tag can, not only work on containers containing liquids but in liquids as well, by reading a UHF Tag placed inside a Gatorade bottle.

Additionally UHF tags not only work on metal, but these tags actually take advantage of the metal background, utilizing it to increase performance. For example, Boeing chose to identify aircraft parts with UHF Tags to streamline maintenance and pre – flight inspection processes. Boeing used a mount – on – metal UHF tag to identify metal objects.

In short, UHF tags are flexible and can be designed to achieve the best performance required on metal and on – or in – liquids.

2. UHF Tags do not provide contained read range, required for item level tracking.

UHF Tags can provide a full spectrum of ranges required, from near field ranges as small as an inch away to 50+ft. Read range is not strictly determined by the frequency. UHF Tag inlays designed to have a shortened read range will be as good (if not better) as HF tags. Antennas can be designed to have a short, long or complete read ranges. Unlike HF Tags, UHF tags allow for flexibility in read range, tags can be designed to function in near and far field applications.

3. UHF Tags are too large and are inappropriate for applications where a smaller footprint is necessary

UHF Tags do not have size constraints. UHF Tags can be designed based on a footprint. Medical UHF labels can be found as small as 9 mm in size. UHF tags provide the flexibility to meet customers’ needs, from short range tags to tags small enough to fit in the cap of a vial to large tags that require robust performance in the longest of read ranges.

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