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  • What is RFID ?
  • Wireless communication and
          the air interface
  • Carrier frequencies
  • Data transfer rate and bandwidth
  • Range and Power Levels
  • RFID System Components
  • Transponders/Tags
  • Basic features of an RFID transponder
  • The Reader/Interrogator
  • RF Transponder Programmers
  • RFID System Categories
  • Areas of Application for RFID
  • Standardisation
    		•
    Carrier frequencies.

    In wired communication systems the physical wiring constraints allow communication links and networks to be effectively isolated from each other. The approach that is generally adopted for radio frequency communication channels is to separate on the basis of frequency allocation. This requires, and is generally covered by government legislation, with different parts of the electromagnetic spectrum being assigned to different purposes. Allocations may differ depending on the governments concerned, requiring care in considering RFID applications in different countries. Standardisation efforts are seeking to obviate problems in this respect. Three frequency ranges are generally distinguished for RFID systems, low, intermediate (medium) and high. The following table summarises these three frequency ranges, along with the typical system characteristics and examples of major areas of application.

    Table 1. Frequency Bands and Applications

    Frequency BandCharacteristicsTypical Applications
    Low 100-500 kHz Short to medium read range Inexpensive low reading speed Access control Animal identification Inventory control Car immobiliser
    Intermediate 10-15 MHz Short to medium read range potentially inexpensive medium reading speed Access control Smart cards
    High 850-950 MHz 2.4-5.8 GHz Long read range High reading speed Line of sight required Expensive Railroad car monitoring Toll collection systems


    A degree of uniformity is being sought for carrier frequency usage, through three regulatory areas, Europe and Africa (Region 1), North and South America (Region 2) and Far East and Australasia (Region 3). Each country manages their frequency allocations within the guidelines set out by the three regions. Unfortunately, there has been little or no consistency over time with the allocation of frequency, and so there are very few frequencies that are available on a global basis for the technology. This will change with time, as countries are required to try to achieve some uniformity by the year 2010.

    Three carrier frequencies receiving early attention as representative of the low, intermediate and high ranges are 125kHz, 13.56 MHz and 2.45 GHz. However, there are eight frequency bands in use around the world, for RFID applications. The applications using these frequency bands are listed in Table 2.

    Not all of the countries in the world have access to all of the frequency bands listed above, as some countries have assigned these bands to other users. Within each country and within each frequency range there are specific regulations that govern the use of the frequency. These regulations may apply to power levels and interference as well as frequency tolerances.

    Frequency range Applications and comments
    Less than 135kHz A wide range of products available to suit a range of applications, including animal tagging, access control and track and traceability. Transponder systems which operate in this band do not need to be licensed in many countries.
    1.95 MHz, 3.25MHz, 4.75MHz, and 8.2MHz Electronic article surveillance (EAS) systems used in retail stores
    Approx. 13 MHz, 13.56MHz EAS systems and ISM (Industrial, Scientific and Medical)
    Approx. 27 MHz ISM applications
    430-460 MHz ISM applications specifically in Region 1
    902-916 MHz ISM applications specifically in Region 2. In the USA this band is well organized with many different types of applications with different levels of priorities. This includes Railcar and Toll road applications. The band has been divided into narrow band sources and wide band (spread spectrum type) sources. In Region 1 the same frequencies are used by the GSM telephone network.
    918-926 MHz RFID in Australia for transmitters with EIRP less than 1 watt
    2350 - 2450 MHz A recognized ISM band in most parts of the world. IEEE 802.11 recognizes this band as acceptable for RF communications and both spread spectrum and narrow band systems are in use.
    5400 - 6800 MHz This band is allocated for future use.
    The FCC have been requested to provide a spectrum allocation of 75 MHz in the 5.85-5.925 GHz band 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.