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A news service reporting on developments regarding the use of radio based tagging transponder systems for commerce and scientific applications. Covering the RFID technologies, EAS technologies and magnetic coupled techniques.


Editorial

Compatibility between the US and Europe radio frequency regions for International trade

Historically if you were not going to operate at 125kHz, then RFID compatibility between these two regions has generally been a mess. 125kHz was chosen by suppliers as it was below the frequency planning of the FCC in the US and hence there were no licensing issues. However ranges of a couple of centimeters were the best you could hope for!

In the UHF frequency band, two divergent approaches were being followed. In Europe generally 420 to 460MHz band was favoured for applications involving RFID. Powers allowed were very low and each country in the present European Union had their own plans and allocated frequencies according to that plan. There were no allocations in the 900MHz band and eventually GSM cell phones were allocated to this spectrum which removed any hope of getting a 900MHz allocation.

In the US, the 400 MHz band was not favoured but instead a wide allocation from 902-928MHz was allocated, and some other applications even moved off this allocation, to encourage RFID development, particulartly for monitoring movement and tolling of vehicles and railstock. The FCC even increased the power allowable in the band to 30 watts ERP although licensing was required.

More recently manufacturers of RFID systems have pushed for a 13.56MHz allocation. This has been successful in Europe with the harmonisation as part of the Unification in Europe, but still ranges are in the 30cm region. However the FCC have also allowed this frequency, but with such a low power that this performance is not achievable in the US.

In the upper UHF band around the microwave oven frequencies there is some compatibility but ranges are limited to 0.5 meters in a passive role and technology is expensive.

Out of the harmonisation of Europe has suddenly appeared a frequency allocation for RFID at 868/9MHz, a frequency that is to be available througout the EU cutting across the former countries individual plans. This is still some 40MHz away from that of the US but if the transponder design has a property called "frequency agility", achieved by having no tuned circuits and wide bandwwidth antenna, then technically it is possible at last to have a tag that can be read in the US and EU regions.

However all was not to be simple and the EU have set a maximum power of only 0.5 watts ERP, only 1.6% of the power allowable in the US. This power is so low that it is similar to that of a cell phone.

One does not know why the EU set the power so low? As the cheapest form of tags are passive type tags, that is they have no battery and receive their energy from the energising field and could be made for less than US$0-20, one must assume that this type was not to be used in Europe and instead active tags, which cost a lot more, have batteries with limited life, and also cause ecological issues with battery disposal were the preferred type according to their reasoning. The 0.5 watt requirement is fifty thousand times below the health reference level so it could not have been for health reasons. Also increasing the power allowable in a band such as used by RFID tags has only an immediate impact on other users within a few meters of the source, as the power density drops as the square of the distance. A person 5 meters from a 1 watt source would experience the same power levels if they moved to 7 meters away from a 2 watt source.

Hopefully RFID will oneday make such an impact that EU based industry and consumers will lobby for the power levels to be raised. This is actually a very similar situation to that of the microwave oven which was also banned originaly in many countries due to its radio spectrum requirements, but consumer pressure has since forced its acceptance in the spectrum planning.

On 0.5 watt ERP a UHF tag has a range of about 30 cms.

Editor

PS: The Editor has been informed unofficially that the EU are expected to significantly increase the powers for UHF RFID in 2004.

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