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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.

Radio frequency issues relating to Transponders

The need to use the radio spectrum and therefore the requirement that RFID system comply with various spectrum management plans for the different trading countries is one of the biggest limitations to the current success of radio frequency identification techniques.

Generally each country in the world manages its own radio spectrum and treats the radio spectrum as a national resource. These plans have evolved over time depending on the needs of the users and industry in those particular countries, resulting in virtually no uniformity of spectrum with application over the worlds regions.

In order to bring a measure of uniformity, the world has recently been dived into three regulatory areas with a view to trying to get some uniformity within the areas. Uniformity will however only be achieved towards the year 2010 as it requires each country to impliment the plans for that region. The regions are:

Region 1

Europe and Africa

Region 2

North and South America

Region 3

Far East and Australasia

The basic frequency bands in which RFID type activities occur in some of the regions around the world are:

Less than 125KHz

Injectable and access control magnetic coupled transponders. In many countries transponder systems operating in this band do not need to be licensed.

1.95 MHz/ 3.25MHz/ 4.75MHz and 8.2MHz

EAS transponder systems used in retail stores

13.56 MHz

Read only, read/write and EAS transponder systems using magnetic coupling - also ISM (Industrial, Scientific and Medical)

Approx 27 MHz

Transponder systems specifically in Australia

430-468 MHz

ISM applications specifically in Region 1 (0.5 watts ERP maximum- country & frequency specific)

856 MHz

Toll road systems in Norway

869 MHz

ISM applications in Region 1 (0.5 watts ERP maximum)

902-928 MHz

ISM applications specifically in Region 2. This band in the USA is very well organised to allow for a multitude of different types of applications with different levels of priorities. Railcar and Toll road applications are but a few of the applications assigned to this band. Recently the band has been divided into narrow band sources and wide band (spread spectrum type) sources. A reciprocal band however does not exist in Region 1 where the same frequencies are used by the GSM telephone network. Existing US Dedicated Short-Range Communication operations, mainly for tolling, use the 902-928MHz frequency band.

2350 - 2450 MHz

This band largely exists due to the uncontrolable success of the microwave ovens. As the ovens use magnetrons that are high power radiators and whose frequency is temperature dependent, normal communication applications could not be accomodated in this band and it was largely left vacant. This band has hence become the preferred band by the regulators for assignment to spread spectrum short range communication links, RFID and generally mass commercial applications which can tolerate interference from the microwave oven sources. Disadvantages of the band are that generally gallium arsenide type circuitry needs to be used as front ends as the performance of conventional silicon has been exceeded. Tags will also generally be active (have battery) as it is difficult to transfer sufficient power.

5400 - 5900 MHz

This band is allocated for future use, but technically is not readily achievable cost effectively with current technologies. It is being targetted particularly for Electronic Toll Collection, where the transponders need to be sophisticated and can use specialised diode and RF sections mounted with digital circuitry; and where the transponders can be more expensive due to their sophistication and function.

The FCC have approved for ruke making a spectrum allocation of 75 MHz in the 5.85-5.925 GHz band for Dedicated Short-Range Communication (DSRC) for Intelligent Transportation Services use.

In France the TIS system is based on the proposed European pre-standard (preENV) for vehicle to roadside communications communicating with the roadside via microwave beacons operating at 5.8 GHz.

Japanese standards developers proposed a DSRC standard operating at 5.8GHz and a transmission speed of 1Mbit/s with a transponder estimated cost of US$80-160

24.125GHz

This frequency is used for alarm systems as well as Police radar, speed measurements as well as automatic opening of market and hotel doors! The typical 9 milliwatt transciever will detect a moving object at 500 meters.

These frequencies are attractive for RFID communication because in most of the world there is no requirement for a licence, only a radiation standard, however at such low powers only reflective (presence) or active tags are practical.

Each and every one of these bands have specific requirements that have to be met, for example power, frequency stability, interference, priority, etc. These conditions are different for virtually every country and no one should use these frequencies without obtaining the necessary permission from their licensing authority.

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