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RFID - is it really radio?

M0DCD

Having started looking at this technology I don't actually think it does fill the criteria of being radio as it's only near field technology. The use of multi-turn loops and the small size (compared to frequency) make most of the technologies in use not actually radiate the combination of fields to generate a "proper" radio signal. I had previously dealt with near field LF applied to enable control equipment, mainly to prevent an operator from controlling a machine further away than was safe. Would a more accurate decription be LFID?

  • Dear Andrew,

     

    I kind of disagree of your below statement. Reason being is that RFID are used in LF, HF and UF bandwidth. Yes, you are right that access control applications are operated by LF RFID. But do bear in mind that HF RFID are also used in application such as an Electronic Road Pricing gantry in Singapore.

     

    So, I guess RFID will be the more suitable if not the most appropriate word that is to be used. But of course, correct me if I am wrong.

     

    Reference Link:

    http://en.wikipedia.org/wiki/Radio-frequency_identification

     

    Cheers

    Edmund

  • in reply to edmund

    Yes, I agree with Edmund. I think first we should clarify what is RF? I think it means the frequency suitable for wireless communication. From extmerely low frequency(low to 30Hz) to extremely high frequency(high to 300GHz) all are radio frequency. But usually we use MHz frequency band becuase the wave band is suitable for communication.

    Then, just as Edmund said, RFID have several band, LF(0-300kHz), HF(3-30MHz), VHF(300-960MHz) and UHF(2.45GHz and above). LF band is very common in door lock application and have no frequency restrict, so it is knowed by most people. But it has some disadvantages such as the distance, the data rate and the antenan size. So we use VHF and UHF in those application need high speed and far distance read/write. And in diffenerent area and countries, the frequency for RFID is different according to the local regulation.

    In addition, I think it is called RFID is not only by it's operating frequency but also by it's technology.Beacuse we will use antenna, transmitter, receiver component which are very common RF components.

    If you have some different view or interesting opinion on RFID, we can discuss more

  • in reply to wendydu

    RFID is ID at radio frequencies - so named aptly. At LF (125 / 134 kHz) and HF (13.56 MHz) the systems use inductive coupling for energy transfer - meaning the fields they employ do not really radiate and are limited to the near field range. Using antennas that would really radiate is not usually permitted and the receiving antennas in the tags wouldn't work well either.

     

    UHF systems on the other hand (840-960 MHz depending on jurisdiction) do really emit signals which can be listened to at hundreds of meters distance - this is not inductive coupling / near field.