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Maximum range (RFID) can function

  1. May 28, 2007 #1
    I need to know the maximum range in which a radio frequency identification device (RFID) can function. What is it limited by?
  2. jcsd
  3. May 28, 2007 #2


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    The max range will vary by device.
    The manufacturer should be able to supply this info.
  4. May 28, 2007 #3


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    Eighteen astronomical units.

    - Warren
  5. May 28, 2007 #4


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  6. May 29, 2007 #5


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    The range is limited by two basic factors. First, there will generally be some limitation on how strong of an RF signal can be used. The limitations may come in the form of government limits (like by the FCC here in the US), in order to limit RF interference with other RF devices in nearby frequency bands. Or the limitations may come in the form of how much power is available for transmission, or how (in)efficient a small transmit antenna may be, etc.

    The second factor is the gain of the receive antenna and the sensitivity of the receive circuit, along with the efficiency of the receive processing string. RFID and ISM band low-noise receivers have improved over the past few years, so as NoTime says, you will need to check with several manufacturers of systems to see what kind of range they are claiming.

    BTW, in addition to those two basic range-limiting factors, you also have the issue of multi-path interference, which further degrades the transfer of energy. The farther you want to go, the more multipath interference will become a hindrance.

    (EDIT: fixed GSM --> ISM)
    Last edited: May 29, 2007
  7. May 29, 2007 #6
    plenty of information i see.
    i'll have to analyse if before i say anything or ask furhter
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