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Thread: alfa usb txpower 0-36 !!! danger??

  1. #11
    Member PeppersGhost's Avatar
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    Streaker is it possible to use a swr meter on wifi type antenna's? I'm not real fimiliar with tuning antenna's, but cb guy's use an swr meter for cb rigs all the time. If not, it sounds like someone needs to make one for wifi.
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  2. #12
    Senior Member streaker69's Avatar
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    Quote Originally Posted by PeppersGhost View Post
    Streaker is it possible to use a swr meter on wifi type antenna's? I'm not real fimiliar with tuning antenna's, but cb guy's use an swr meter for cb rigs all the time. If not, it sounds like someone needs to make one for wifi.
    You'd need an SWR Meter that's able to function in that range. Like I said earlier, generally manufacturer's will tune their antenna's for an SWR of 1.5 on an average power output. Problems with that arise when you start messing around with connecting external antenna's. Each connection that you make, through pigtails and such is going to add to the SWR, as well as to the db loss. As your SWR approaches 3.0 you're going to see your reception and transmission degrade.

    Back in the CB days, it was a big deal to get the antenna's tuned up and get the SWR down to 1.1, of course you can never reach an SWR of 1:1 because that would mean you'd have a 100% efficient antenna, which just isn't possible.

    I have a meter here that goes up to the 900mhz range that I could use to calculate SWR, but it isn't an SWR meter per sea. It will measure forward and reverse power and then you can calculate it from there. But I've never actually seen one myself that operates in the 2.4ghz range.
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  3. #13
    Member PeppersGhost's Avatar
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    yea. Well I see this one on "googland" (dumb question from me). It needs 30 to 100mw. So, not so good really for 500mw. This looks like new project.

    http://pe2er.nl/wifiswr/forsale.htm
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  4. #14
    Member PeppersGhost's Avatar
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    I see what you're saying about commercial wifi antenna's streaker. It looks like you would need an swr meter in the correct wattage and freq range. And then maybe a custom antenna wound by the dali lama.
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    The Dalai Lama wouldn't have the time. He watches to much tv.
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  6. #16
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    Where did you find that 1dbm = 65mw?????



    dBm = log10 (mW)*10
    mW =10^(dBm/10)

    40 dBm 10.00 watts
    36 dBm 4.00 watts
    30 dBm 1.00 watts
    27 dBm 500 milliwatts
    26 dBm 400 milliwatts
    25 dBm 320 milliwatts
    24 dBm 250 milliwatts
    23 dBm 200 milliwatts
    22 dBm 160 milliwatts
    21 dBm 130 milliwatts
    20 dBm 100 milliwatts
    15 dBm 32 milliwatts
    10 dBm 10 milliwatts
    5 dBm 3.2 milliwatts
    4 dBm 2.5 milliwatts
    3 dBm 2.0 milliwatts
    2 dBm 1.6 milliwatts
    1 dBm 1.3 milliwatts
    0 dBm 1.0 milliwatts
    1- dBm 0.79 milliwatts
    5- dBm 0.32 milliwatts
    10- dBm 0.1 milliwatts
    20- dBm 0.01 milliwatts
    30- dBm 0.001 milliwatts
    40- dBm 0.0001 milliwatts
    50- dBm 0.00001 milliwatts
    60- dBm 0.000001 milliwatts
    70- dBm 0.0000001 milliwatts
    80- dBm 0.00000001 milliwatts

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