How to Conform to Regional Regulations when using RFID
Introduction
Regional regulations are rules put in place by individual countries to regulate the transmit frequency and output power of RFID systems. In any country, these regulations are important to know and abide by when purchasing and deploying an RFID system.
Here are the most common questions and the relevant answers about RFID power regulations.
In terms of RFID, what is regulated?
- Frequency or frequency range of transmissions
- Power levels of RF Emissions
- RFID Readers, Active Tags, and Certain Passive Tags
Why are regulations put in place?
Most governments have regulating bodies, or commissions that create and oversee regulations involving country-wide standards relating to radio communications. For the RFID portion of this, these commissions oversee RF frequency, power emissions, and ensure that the RFID equipment manufactured or imported in the country is certified for use. The Federal Communications Commission or the FCC, is the governing body that oversees these standards for the United States in accordance with the Federal Communications Act. The European Telecommunications Standards Institute better known as ETSI, sets the standards for the European Union for all Information and Communication Technologies which includes RFID.
Frequency or Frequency Range of Transmissions
Frequency ranges are regulated because each country allocates specific frequency bands to certain types of communication. If communication types are fixed to one specific range and monitored, it reduces interference. Radiating RF waves on the wrong frequency range in a country produces interference with other channels that could be allocated to more critical communications like military transmissions, aviation transmissions, or satellite communications.
Power levels of RF Emissions
Regulations on reader emissions are put in place to ensure the power output from the RFID reader does not exceed a predefined level that can interfere with other radio waves in the vicinity. If an RF system is in close proximity to another while exceeding the maximum permitted power level, it most likely will interfere with the other system causing missed reads, lost reader to tag or tag to reader communication, or application failure, and also may cause unintended operation in the other system.
RFID Readers, Active Tags, and Certain Passive Tags
Most devices that radiate RF waves must be certified by each country’s government in order for it to be used, manufactured, or imported into that country. Certifications enable countries to enforce communication standards, especially for validating that the reader or tag cannot output more power than the country allows.
Certain passive tags are also subjected to federal certification in order to be sold for and used in hazardous environments or to pass unique, application-based specifications.
How do regulations differ from country to country?
Frequency
Countless variables go into approving a frequency range and a maximum output power for each country, which is why it can vary greatly between countries.
Speaking strictly in terms of frequency ranges, it would be incredibly difficult to have a set, universal frequency band for UHF RFID. This is mostly due to the late adoption of UHF RFID and the limited amount of space still available in the mid-range of the Electromagnetic Spectrum. One example of this is that North America uses 902-928 MHz, but Europe already uses parts of that frequency range for military communications, meaning that it had to determine another frequency range for RFID.
Most countries choose and adopt one of the two common, pre-existing ranges – either 865 – 868 MHz or 902 – 928 MHz, and enable the use of that range country-wide. However, there are a few countries that have more distinct regulations that must be followed, below are the two most common outliers.
- A common frequency outlier in some countries is to have two specific smaller bands allocated for UHF RFID. Generally, like above, this is due to another communication channel being allocated in the middle of a larger band such as 902 – 928 MHz.
- Some countries allow for UHF RFID systems to be used, but only after obtaining a license through the government. More commonly, countries only require licenses for certain bands in the frequency range or for using a certain frequency band at or over a specific output power. If an UHF RFID user does not get a license before going forward, they could be subjected to large fines or company shut downs.
Output Power
Power output in dBm or watts varies per country and just depends on what the government has decided works best with their country’s pre-existing standards. Power in watts is usually either 2 watts ERP or 4 watts EIRP.
How do I know if I am within regional regulations?
First and foremost, check GS1’s UHF frequency regulations to determine your country’s exact specifications. Their document contains a list of each country that has adopted GS1 regulations and documents each country’s allocated frequency range, output power, and any other specifics that might be needed to set up an RFID system in that country.
Frequency range will be easy to determine because the reader or receipt from the purchase of any RFID equipment should denote the frequency range. Most often, readers cannot be sent to countries that they are not certified in, but it is still important to double check that you are using the correct frequency for your country.
When it comes to output power, once you have determined what the regulations are in your country, the next step is to calculate your system’s output power.
Principle to Know
Effective Radiated Power (ERP) vs. Effective Isotropic Radiated Power (EIRP)
The technical difference in the two is that ERP refers to the gain in relation to a half-wave dipole antenna and EIRP refers to the gain in relation to an ideal isotropic antenna. Some countries provide output power in ERP and some provide it in EIRP, and there is a big difference between them in terms of how they are calculated.
Below is the relation between ERP and EIRP in terms of Watts, and dBm.
EIRP (W) = 1.64 * ERP (W)
EIRP (dBm) = ERP (dBm) + 2.15
Calculating Output Power
To calculate output power, you need the following information:
-
Reader Transmit Power in Watts, mW, or dBm
Radiated power can be expressed multiple ways, but for RFID, the most common ways are Watts, milliwatts (mW), and dB referenced to one milliwatt (dBm).
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Cable Loss in dB
To calculate output power in ERP or EIRP the cable loss in dB is required. To learn more about cable loss check out this article.
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Antenna Gain in dBd or dBi
Antenna gain can be expressed in a few different ways depending on the antenna and the manufacturer. The most common ways to express gain are dBi, dBic, dBd, and dbiL.
To see the conversion tables and equations for converting the above information, click here.
Use the following equations to calculate the EIRP or ERP of your system. Decide which to calculate (ERP or EIRP) by checking your country’s frequency regulations, as noted above.
_____ dBm – _____ dB + _____ dBi = _____ dBm EIRP
_____ dBm – _____ dB + _____ dBd = _____ dBm ERP
Below is an example of calculating EIRP and ERP.
Transmit Power = 31.5 Cable Loss = 3 dB Antenna Gain = 6 dBi
31.5 dBm – 3 dB + 6 dBi = 34.5 dBm = 2.82 W EIRP
31.5 dBm – 3 dB + (6 dBi – 2.15 dB = 3.85 dBd) = 32.35 dBm = 1.78 W ERP
How can I make sure to stay within regulations? What if I’m over?
If you use the calculations above to determine output power and it is higher than what is allowed in your country/area, there are a few different ways you can adjust your system to stay within regulations. The first, and easiest, way is to simply reduce the transmit power on your RFID reader. Turning down the transmit power, depending on how far over regulations the system currently is, can keep your system from violating the ERP or EIRP maximum.
Two other ways to reduce the output power are:
- Use a lower gain antenna
- Use a cable with appropriate attenuation loss to compensate for the power level.
Exceeding a country’s regulations can cause problems with other RF systems in the area and call government attention to your system. If you are exceeding the regulated power output, you or your company could be fined or the application could be shut down depending on the country.
Remember to check and see if your country has any further instructions on using RFID in that area, like special licenses.
How can I learn more about RFID regulations?
Check out GS1’s website to learn about RFID regulations, or go to the Communications area of your government to learn about specific country by country information.
Conclusion
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