If you have used RFID technology in your business, you must have certainly come across the terms LF, HF, and UHF. You might have also heard about tags compatible with each of these frequencies.
All three are wireless communication standards used for short-range communications. So what is the difference between them? Here’s a comprehensive guide:
To help you understand the terms LF, HF, and UHF, we will first discuss the meaning of frequency. It is the number of times a periodic process occurs within a unit of time.
Different frequencies have different corresponding wavelengths and cycles per second (or hertz), which are represented by the terms kilohertz (kHz, thousands of cycles per second), megahertz (MHz, millions of cycles per second), and gigahertz GHz representing billions of cycles per second.
Wavelengths refer to the distance between one wave crest to the other. The frequency of any wave is inversely proportional to its wavelength. This means that HF (high-frequency waves) have a short wavelength while LF (Low-Frequency waves) have a long wavelength.
This concept is critical as it affects the functionality of various frequencies. For example, it is easier to intercept short wavelengths than long wavelengths. As such, HF waves cannot be used in presence of other radio wave sources. If you do, it will be disrupted and its efficacy compromised significantly.
What is LF, HF, and UHF?
LF has a frequency range between 30 kHz and 300 kHz. It can pass through water and soil easily, making it ideal for communication via submarine or underground.
On the other hand, HF has a frequency range between 3 MHz and 30 MHz. It is also known as high frequency or short wave. Finally, UHF has a frequency range between 300 MHz and 3 GHz.
Which Frequency Should You Use?
As you know now, the choice of which frequency to opt for depends on the distance of communication required. Let us now discuss some common scenarios:
Scenario 1: Medium-Distance Communication
In this scenario, you need to communicate from a central location to multiple locations within a particular region. Thus, it is known as one-to-many communication. Some of the most common examples include radio and television broadcast, cellular communication, and two-way radio.
For the best effect, you need to choose a frequency that can be transmitted over long distances with minimal or no interference. Thus, frequencies like UHF or Super High Frequency (SHF) are most suitable for this scenario.
Scenario 2: Short-Distance Communication
In this scenario, you need to communicate between multiple locations within a particular region. Thus, it is known as many-to-many communication. Some of the most common examples include wireless microphones and short-range radio frequencies like Bluetooth and Wi-Fi.
For the best effect, you need to choose a frequency that can be transmitted over short distances without any interference. Thus, frequencies like LF are most suitable for this scenario.
In summary, LF is ideal when communication needs to be across longer distances and has little chance of outside disruption. UHF offers greater bandwidth and signal strength, and it is ideal when all locations are within the same general vicinity. HF offers greater bandwidth over shorter distances, and thus it is convenient for situations where groups of people need to be in close range to each other.
LF, HF, and UHF RFID Systems
When choosing an RFID tag, consider factors such as size, shape, read distance, and frequency. The kind of technology used for an LF RFID system is different from that of an HF RFID system. Here are the differences:
LF RFID Tags
LF RFID tags have different features that set them apart from the rest. They include:
- Short Read Range. These tags are only ideal when you’re using them over a distance of up to 10 centimeters.
- Low Interference. The tags have a very low chance of radio wave interference, making them the best for use in an area populated with electronics equipment.
- Low Frequency (approximately 125 MHz). These tags are capable of reading data at their specific LF frequency, which is ideal when performing proximity identification.
- Slower Read Range. This is because of the tag’s lower read power, which means that it takes a longer distance for the tag to send a signal back to the reader.
These features make the LF tags ideal for use in hospitals and healthcare institutions, which is why the majority of them are designed to be resistant to biocompatible liquids. They can also be used for tracking livestock as they work optimally in moist conditions.
HF RFID Tags
Some of the unique features of HF RFID tags include:
- Stronger Signal (up to 10 cm to 1 meter). This allows for high read accuracy and effective identification even over long distances.
- High Frequency (13.56 MHz). This ensures that these tags can be used with other RFID readers without any interference.
- Moderate Chances of Interference. If you’re using these tags in an area populated with radio waves, you might experience a few interferences, but their chances are not as high as those of UHF tags.
- Can Work on Liquid and Metallic Surfaces. While they are more likely to be affected by liquid surfaces, they can still work relatively well even when used on metals.
HF RFID tags are ideal for product tracking and inventory management because they can be read from a distance without any need for direct contact. These tags can also be used in contactless payments and ticketing.
UHF RFID Tags
UHF tags are the best in terms of frequency because they have the highest RFID operating frequencies. Some of their unique features include:
- Higher Frequency (915 MHz to 960 MHz). This offers increased read range and accuracy.
- Increased Read Range. UHF tags offer a read range of approximately 12 meters.
- High Interference. If you’re using these tags in an area with high radio wave interference, it will affect their performance somewhat.
- Cannot Be Read on Liquid and Metallic Surfaces. Because of the higher frequencies, UHF tags are not ideal for use on liquid or metallic surfaces.
UHF RFID tags have shorter wavelengths and can be intercepted by metallic and moist environments. However, they are cheap and easy to manufacture.
They are used in asset tracking, transportation, and security management.
Trends in Radio Frequency Industry
The UHF technology is becoming increasingly dominant in the RFID industry. This rise in popularity is due to its ease of manufacturing, comparatively low price, and higher accuracy resulting from its longer read range.
The LF tag is ideal for use in applications where proximity tags are needed to be used within a short range of half a meter. It also has the fastest read speed among all three technologies. On the other hand, HF tags are best suited for product tracking and inventory management because of their read range and accuracy.
UHF tags are mostly used for security because of their high read range and long read time, making them suitable for use in crowded environments.
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