max safe power for WRT54GS and exposure time

Discussion in 'Wireless Internet' started by, Apr 4, 2006.

  1. Guest

    I have two WRT54GS talking though a 800-900 foot distance through
    trees. There's no other way. I have a 15 db Yagi on one end, and
    will be purchasing something similar for the second end. Right now,
    I'm seeing -91 (+-1 or 2 points) signal rhough the DD-WRT wireless
    status, This is with the transmit power turned up from 28 mw to 200 mw
    (yes two hundred).

    Has anyone else had the power turned up this high? If so, how long can
    I expect these boxes to last?

    Can anyone recomend a nice flat 15-ish db antenna I can mount on the
    second box. I'd prefer flat, as a yagi would be an eye sore.


    ON a side note, what would be the minimum safe distance/time exposure
    for 200 mw with a 15 db yagi on 2.4 ghz?
    , Apr 4, 2006
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  2. hath wroth:
    Yep. Two of my friends locally. Lasted about 2 weeks and blew. I
    have one of these V4 routers but haven't had time (or inspiration) to
    do an autopsy.
    Oh, any one of these will work:
    At 1ft away from the antenna, the RF exposure is 0.5 mw/cm^2.
    The maximum permissible exposure for an uncontrolled environment is
    1.0 mw/cm^2. You're safe to about 0.8ft away from the antenna.
    Jeff Liebermann, Apr 4, 2006
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  3. Guest

    So if I move from the standard antenna to a 14 db flat panel on the
    remaining 'stock' linksys, will that give me more than a 10db
    improvement? What's the rating of the stock antenna?

    If so, then will I get equivallently the same 'reception/transmission'
    quality if I reduce the transmission power from 200 mw on both ends to
    just 20 (rather, 28 mw, the stock).

    --Now, I'm still getting fade during the day. How high can I put the
    transmitters for general use? 40 mw? 48 mw? 50 mw?
    , Apr 5, 2006
  4. John Navas Guest

    [POSTED TO alt.internet.wireless - REPLY ON USENET PLEASE]

    It should -- the gain of a stock "rubber ducky" antenna is about 2 dBi.

    As an alternative, see
    John Navas, Apr 5, 2006
  5. The stock antenna is essentially a coaxial vertical dipole antenna.
    Gain is about 2dBi. A 14dBi flat panel will give a maximum of 12dB
    gain over the stock antenna. However, don't forget to subtract coax
    cable and connector losses from the 12dB.
    Most non-reflector antennas have the same gain in transmit and
    receive. 14dBi gain in transmit and receive. However, if you use a
    dish, the gain is somewhat different betweeen transmit and receive
    depending on how well the feed illuminates the dish surface. In
    general, the transmit gain of a dish is slightly less than the receive
    gain because the feed's tendency to "overspray" the dish.
    Going from 200mw to 20mw is a factor of 10. In dB, that's a change
    dB = 10 * log(10) = 10dB
    Are you sure it's fade and not inteference from other networks that
    only operate during the day?
    I really don't know. My guess is 50-100mw max. I know that 250mw
    will eventually blow up the transmitter, but I don't know exactly what
    power is safe. There's also the not so minor issue of FCC type
    certification. I'll pass. Anyway, going from 35mw to 100mw is
    wasted. It's only
    dB = 10 * log (100/35) = 4.6dB
    I suggest you work on the antenna part of the puzzle and leave the
    power alone.
    Jeff Liebermann, Apr 5, 2006
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