"Cantennas" to increase wifi transmitter range

Discussion in 'Home Networking' started by DJ Craig, Nov 27, 2005.

  1. DJ Craig

    DJ Craig Guest

    What are some do-it-yourself ways that you can increase the range of a
    wifi transmitter? I've heard stuff like you can make a "cantenna" by
    putting a pringles can over the antenna, and that's supposed, but it
    didn't work for me. I've also heard that this is illegal because of
    the FCC. Is that true, and if so, why? I have a syslink wifi
    transmitter/router/switch. It's supposed to work at 150 feet, but it's
    definitely not doing that for me. It's in a wooden house. I have it
    sitting in a room where there is a big cathode ray tube TV strait
    through the room for it, could that me interferring with it? Even
    though when it's turned off?
     
    DJ Craig, Nov 27, 2005
    #1
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  2. [alt.comp.networking.connectivity deleted because Newsguy claims it's
    bogus]
    Better antenna or better location. Antennas can vary from simple
    reflectors:
    http://www.freeantennas.com
    to various forms of corner reflector, biquad, dish, panel, patch,
    yagi, omni, ad nausium antennas. Note that the antenna does not
    generate any RF. It merely redirects it. If you want to increase the
    antenna gain in one direction, there is a corresponding loss of gain
    in other directions. Tailoring the antenna pattern to your
    unspecified requirements is paramount in the selection of an
    appropriate antenna.
    Please tell me you didn't hear someone recommend putting a pringles
    can over an omni directional antenna found one a typical access point.
    That won't work.
    If you're in Tennessee, why did you post this question to a UK
    newsgroup?

    It's not totally illegal to modify a wireless system by replacing the
    antenna. Note that the rules changed on Nov 22. Section 15.204(c)(4)
    proclaims:
    Any antenna that is of the same type and of equal or less
    directional gain as an antenna that is authorized with the
    intentional radiator may be marketed with, and used with, that
    intentional radiator. No retesting of this system configuration
    is required.
    What this means is that you can't change the type of antenna that is
    supplied or use a version that has a higher gain, unless the
    manufactory has bothered to type certify their system with the higher
    gain antenna. In other words, most of the aftermarket antennas are in
    violation of 15.204(c)(4).
    Why is it true or why is it so? I guess I have to answer both
    questions. It's true because the FCC is deathly afraid that congress
    might realize that the FCC's protectionist mentality toward large
    monopolies, and the obvious and phenomenal success of unlicensed
    services, might suggest to an elected official of moderate
    intelligence that the FCC is largely obsolete and not serving any
    useful purpose.

    As to why it is so, the rule was established to all manufacturers to
    offer for sale aftermarket antennas without requiring recertification.
    Prior to about 2002, replacement of antennas was totally prohibited.
    That's nice. Any particular model number?
    Fine. How far are you going? How fast? How many walls are you going
    through? Wood is not transparent to RF. Got any foil backed
    insulation in the walls? How about antique foil backed wallpaper?

    Does it work when your unspecified client radio (it takes two to
    tango) is in the same room as the Syslink something? In other words,
    if you remove the walls and range issues, does the system work? It's
    possible that either end is busted, misconfigured, or getting trashed
    by intereference.
    No. The TV set is probably not causing problems. The usual sources
    of intereference are other 802.11b/g systems, municipal wireless
    networks, microwave ovens, 2.4Ghz cordless phones, wireless security
    cameras, and anything else that belches 2.4GHz.
     
    Jeff Liebermann, Nov 27, 2005
    #2
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  3. Do you have a big aquarium in the way? Seriously, that can interfere with
    the signal.
     
    Joseph Stewart, Nov 27, 2005
    #3
  4. DJ Craig

    DJ Craig Guest

    No, our fish are in an outside pond and I don't think they eat radio
    signals ;-)

    But the TV is a 32 inch Sony CRT in the next room, right behind the
    router. Of course it has a lot of big coils and a very thick glass
    screen that might behave the same way as an aquarium. In fact it would
    make quite a good aquarium.

    Do you know if is possible to put an extension arial on the router.
    This model has two antenae.
     
    DJ Craig, Nov 27, 2005
    #4
  5. DJ Craig

    DJ Craig Guest

    http://www.jefatech.com/product/MM24-5RD

    The above site actually advertises an extension antenae for this
    purpose. I might need two. But I would still be interested in the story
    about a cantenna or any other Do-it-yourself method.
     
    DJ Craig, Nov 27, 2005
    #5
  6. Joseph Stewart wrote in
    vUjif.16716$:
    Likewise, if you put the access point in the loft to get the aerial as high
    as possible to increase the range, beware of the header tank for the hot
    water: it will absorb almost all the signal sent in that direction - as I
    found when I put my parents' wireless adaptor in the loft: there was a huge
    "shadow" on the side of the house shielded by the tank. The other problem
    was overheating of the wireless adaptor in the summer heat up in the loft,
    which isn't so much of an issue at this time of year now it's -2 deg C
    outside!

    Many people don't realise that a large tank of water (even if the tank is
    made of plastic) will absorb wireless network signals because 2.4 GHz is the
    resonant frequency of water - which is why food (which contains water) heats
    up in a microwave oven and why this frequency is available for short-range
    wireless networking because it is useless for long-range transmission since
    water in the atmosphere will attenuate the signal.
     
    Martin Underwood, Nov 27, 2005
    #6
  7. DJ Craig

    Bob Alston Guest

    Take a look at my web site for information on the cantenna I used with
    great success.

    http://members.cox.net/tulsaalstons...th Compact - Dongle USB Wireless Adapter .htm

    http://members.cox.net/tulsaalstons/my-tin-cantenna2.htm

    If you do a search for "cantenna" in newsgroup alt.internet.wireless you
    should find LOTS of info (I found 341 entries).

    Bob
     
    Bob Alston, Nov 27, 2005
    #7
  8. DJ Craig

    Conor Guest

    That's because you have to actually make an antenna out of the pringles
    tin, not just stick it over the existing antenna, fuckwit.
    You're posting to a UK group and the FCC have nothing to do with us.
     
    Conor, Nov 27, 2005
    #8
  9. DJ Craig

    DaveC Guest

    Thus spake DJ Craig:
    It's not the aquarium's glass that causes problem for wireless signals; it's
    the water. Water is death to wireless signals. That's why trees are such a
    hinderance to wireless; leaves "look" like little bags of water to the
    wireless devices.

    If the TV is such a big concern for you, experiment by putting your router on
    top of the TV. Does that make your reception better?
    Many antennae available to connect to your router.
    --
    Please, no "Go Google this" replies. I wouldn't
    ask a question here if I hadn't done that already.

    DaveC

    This is an invalid return address
    Please reply in the news group
     
    DaveC, Nov 27, 2005
    #9
  10. DJ Craig

    Rob Morley Guest

    It's a bit more complicated than that - there are plenty of websites
    that tell you how to do it properly.
    Here in the UK we don't worry too much about the FCC :)
     
    Rob Morley, Nov 27, 2005
    #10


  11. Cross posted to
    alt.comp.networking.connectivity,alt.internet.wireless,comp.sys.mac.com
    m,uk.comp.home-networking

    As such, its not exclusive to the UK.


    DMK
     
    D. Kirkpatrick, Nov 28, 2005
    #11
  12. DJ Craig

    iejovrh Guest

     
    iejovrh, Jan 17, 2006
    #12
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