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Thread: Wireless Range

  1. #51
    My life is this forum Barry's Avatar
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    Quote Originally Posted by KillaGreen View Post
    Before i say anything... is it illegal to make an antenna for your wifi stick ? and where ?

    KillaGreen
    As long as you stay under the transmit power limits your country states, then I don't see why it would be illegal.
    Of course, if you really wanted to have some fun, go to Wal-Mart late at night and ask the greeter if they could help you find trashbags, roll of carpet, rope, quicklime, clorox and a shovel. See if they give you any strange looks. --Streaker69

  2. #52
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    Sweet, cause a cantenna is pretty much passive gain eh, and yeah cantenna's do work and they will increase your range, but don't expect a miracle with a can but you could allways attatch the can to a dish, like so many have on google, (a good size for the can I got from wikipidia was 8.5cm X 14.5cm with the hole in the can at 1.25cm from the back) all of the sizes are based on the wavelength of 2.4 GHz frequency. And a while ago i remember calculating out the proper size dish for 2.4 GHz signals, and it was roughly 3 meters! lol but don't worry because all parabolic dishes have the same focal point characteristics (but 3m would be the ideal size :P).

    As for distance, people have reported distances in the km range with simply a recycled can and dish.

    KillaGreen

  3. #53
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    Speakng of dishes, the AB9IL antenna projects were moved to a new URL:

    http://www.ab9il.net/wlan-projects/wifi1.html

    Articles for building large parabolics and helicals. The 0.8 meter TV dish works well over here, through trees, bushes, and other obstructions. Helical good too.

    Also how to connect external antennas to Linksys wusb54gc and Belkin F5D7050.
    True security is based on open and rigorous probing of our strengths and weaknesses. Yeah, and life is too short for hyperbole, metaphor, and BS.

  4. #54
    Just burned his ISO Nokii's Avatar
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    Quote Originally Posted by theprez98 View Post
    When searching for a wireless card, people often want to find one with the best range.
    ...
    As 802.11b/g uses 2.4 ghz, which operates like any other radio frequency signal, we can use the basics of
    RF signal propagation to determine range. There are five basic components which effect signal propagation:

    *Transmit power
    *Transmit antenna gain
    *Frequency and distance (path loss)
    *Receiving antenna gain
    *Receiver sensitivity

    There are other factors which effect signal loss as well: cable losses, RF opaque materials in the signal path, etc.

    Because wireless communication is a two way process, we may also have to include the same five factors in reverse.
    While 'transmit power' referred to your wireless card, on the return trip 'transmit power' refers to the access point.
    Likewise, 'receiver sensitivity would refer to your card as opposed to the access point, and so on.
    ...
    I'll add that there is one more thing. MIMO.

    MIMO enhances NLOS (Non-line-of-sight) propagation and cancels reflections. MIMO offers significant increases in data throughput and link range
    without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and
    link reliability or diversity (reduced fading).

    Sources:
    hxxp://en.wikipedia.org/wiki/Non-line-of-sight_propagation#Passive_random_reflections
    hxxp://.atheros.com/news/xspan.html
    hxxp://en.wikipedia.org/wiki/Multiple-input_multiple-output

  5. #55
    Senior Member ShadowKill's Avatar
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    Quote Originally Posted by Nokii View Post
    I'll add that there is one more thing. MIMO.

    MIMO enhances NLOS (Non-line-of-sight) propagation and cancels reflections. MIMO offers significant increases in data throughput and link range
    without additional bandwidth or transmit power. It achieves this by higher spectral efficiency (more bits per second per hertz of bandwidth) and
    link reliability or diversity (reduced fading).

    Sources:
    hxxp://en.wikipedia.org/wiki/Non-line-of-sight_propagation#Passive_random_reflections
    hxxp://.atheros.com/news/xspan.html
    hxxp://en.wikipedia.org/wiki/Multiple-input_multiple-output
    I have to say Nokii, these first few posts you've made are very impressive. I'm glad to see another member of the community offering up as much as you have, and as quickly as you have. Let it be known that your participation within this community is very much appreciated and hasn't gone unnoticed....



    "The goal of every man should be to continue living even after he can no longer draw breath."

    ~ShadowKill

  6. #56
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    Lots of great info on antennas here guys but I've found out the hard way during a brief stint in pirate radio that to get the best signal strength (ie. best propagation) you need to make sure that your aerial is at least 1 wave length off the ground and should be 1 wavelength long.

    Since 802.11 is 2.4 GHZ and wavelength = speed of light / frequency

    Wavelength = 299,792,458 / 2,400,000,000 = 0.12491352416666666 meters

    12.49 cm = 4.9 inches

    So if you want best results from your antennas make sure they're at least 4.9 inches away from the walls or desktop they're sat on (how many of us have them sat in a corner?) and ideally they should be 4.9 inches long.

    Of course since each wifi channel has a slightly different frequency we could tailor an antenna to a channel:

    ch1: 2.412
    ch2: 2.417
    ch3: 2.422
    ch4: 2.427
    ch5: 2.432
    ch6: 2.437
    ch7: 2.442
    ch8: 2.447
    ch9: 2.452
    ch10: 2.457
    ch11: 2.462
    ch12: 2.467
    ch13: 2.472
    ch14: 2.484

    Though I think we'd only be talking about a milimeter or so probably not worth it .

  7. #57
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    Quote Originally Posted by madferret View Post
    Lots of great info on antennas here guys but I've found out the hard way during a brief stint in pirate radio that to get the best signal strength (ie. best propagation) you need to make sure that your aerial is at least 1 wave length off the ground and should be 1 wavelength long.

    Since 802.11 is 2.4 GHZ and wavelength = speed of light / frequency

    Wavelength = 299,792,458 / 2,400,000,000 = 0.12491352416666666 meters

    12.49 cm = 4.9 inches

    So if you want best results from your antennas make sure they're at least 4.9 inches away from the walls or desktop they're sat on (how many of us have them sat in a corner?) and ideally they should be 4.9 inches long.

    Of course since each wifi channel has a slightly different frequency we could tailor an antenna to a channel:

    ch1: 2.412
    ch2: 2.417
    ch3: 2.422
    ch4: 2.427
    ch5: 2.432
    ch6: 2.437
    ch7: 2.442
    ch8: 2.447
    ch9: 2.452
    ch10: 2.457
    ch11: 2.462
    ch12: 2.467
    ch13: 2.472
    ch14: 2.484

    Though I think we'd only be talking about a milimeter or so probably not worth it .
    Absolutely, positively, NOT true (well, the frequencies and the channel numbers appear to be true).

  8. #58
    Senior Member ShadowKill's Avatar
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    Quote Originally Posted by SLK001 View Post
    Absolutely, positively, NOT true (well, the frequencies and the channel numbers appear to be true).
    An explanation of why not would be beneficial to those that don't know any better....



    "The goal of every man should be to continue living even after he can no longer draw breath."

    ~ShadowKill

  9. #59
    Senior Member Thorn's Avatar
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    Quote Originally Posted by ShadowKill View Post
    An explanation of why not would be beneficial to those that don't know any better....
    Short answer, without going into the physics of antenna design: You use wave fractionals. Quarter-wavelength and half-wavelength antennas are very common. As long as the antenna's radiating element resonates to the wavelength it should work.
    Thorn
    Stop the TSA now! Boycott the airlines.

  10. #60
    Senior Member ShadowKill's Avatar
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    Quote Originally Posted by Thorn View Post
    Short answer, without going into the physics of antenna design: You use wave fractionals. Quarter-wavelength and half-wavelength antennas are very common. As long as the antenna's radiating element resonates to the wavelength it should work.
    Oh no, I understand fully brother, I was speaking on behalf of those less informed and too shy/nervous/whatever to speak up.



    "The goal of every man should be to continue living even after he can no longer draw breath."

    ~ShadowKill

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