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RFID vs RF IC through/underwater

Discussion in 'General Electronics' started by ChronoFish, Nov 5, 2003.

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  1. ChronoFish

    ChronoFish Guest

    Hi there,

    From my understanding RF-Tag technology is still sketchy so maybe it's
    not the best solution for my need.

    What I need is a small transmitter operating at a range up to 1 meter
    (greater than 2 meters is actually not desirable). I am looking for
    frequencies no higher than 27 MHz as the medium the application is
    operating in is water or a water/air combination.

    Most of the RFICs that I have found begin their operation at 100MHz
    and tend to be in the 300MHz - 450MHz range. I believe this will be
    too high for my needs.

    TI produces RFID chips in the 134kHz and 13MHz range and this seems
    very desirable (has a range of 1 meter and has a package size of only
    1mm x 32mm). What is holding me back here is the cost of the readers.
    I believe part of what makes the cost so high is that the reader needs
    to generate a large magnetic field to power multiple transmitters in a
    relatively large area (1 meter radius?). My thought here was to
    combine the RFID chip with it's own powersource. Now the power source
    only needs to work in the 1 - 30 mm range, and only for a single

    Any idea of what this power source would look like? I realize it may
    double or triple the size of the RFID package - and that's okay - much
    larger than that may not be. The power doesn't need to be continuous,
    but I would like to be able to broadcast 2-3 times a second or so
    using a quarter size battery.

    Looking forward to your suggestions and feedback.

  2. Tom

    Tom Guest

  3. Rich Grise

    Rich Grise Guest

    Actually, water is opaque to most, if not all, of the RF part of
    the spectrum. You'd be much better off with a tiny sonar pinger -
    you could probably get a piexo element just a few mm across ...

    Good Luck!
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