PC Card and Range Extender Antenna

Discussion in 'Wireless Internet' started by Rich, Nov 4, 2003.

  1. Rich

    Rich Guest

    Hello group,

    Right - here's the situation. I've just purchased an Alvarion DS-11b PC Card
    for my laptop, which has an external antenna connector on it. Specs on this
    card are available at:

    The antenna I purchased is a 7.8dbi gain, 2400MHz VSWR 1:5:1 antenna.

    I purchased this so that I could connect to my wireless network about 400
    metres from my house (in direct line of sight). At the bottom of our garden
    is a large out-house type building in which I wish to be able to gain access
    to my home network which has broadband internet.

    NOW then.... when I use the card on it's own without the antenna, Windows XP
    reports that the signal strength is "Very Low"/"No Signal".

    My question is, when one plugs in the high-gain antenna expecting it to
    imrpove signal quality, why does the signal not get any better at all?

    Any ideas group?

    Please help!


    Rich, Nov 4, 2003
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  2. Rich

    Dave Guest

    The higher the gain the antenna has the thinner the radition pattern is from
    the antenna (top to bottom) a dipole has a dougnut shapped pattern and as
    you go up in gain you end up with a flat disc, it's possible that if your AP
    is upstairs in your house and you are downstairs (in the garden) with your
    high gain antenna then you could be under the radiated signal (in simplistic
    terms that is), why don't you use the 'pigtail connector that goes to your
    new antenna and have a go at making a 'cantenna' just search the web for
    this to find some designs, they work very well.

    Dave, Nov 4, 2003
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  3. Rich

    Rich Guest

    Hi Dave,

    OK, so what you're saying is that if I picture (in simplistic terms!) the
    radiation pattern as a sphere, when I increase the antenna's gain I am
    in-fact squashing the 'depth' of this sphere - in even more incredibly
    simplistic terms!! - therefore pushing it towards 2D?

    My AP is indeed upstairs, and I was downstairs. Although our house is a
    standard size (three storey) this could be the mechanism at work.

    Could this therefore be corrected by position the AP so that it's
    omni-directional antennas are mounted horizontally?


    P.S. Please forgive the ignorance!!!! :)
    Rich, Nov 4, 2003
  4. Rich

    Dave Guest

    Hi Rich,

    Your description is spot on, when you tested your high gain omni antenna did
    you try angling it so the (for want of a better word) side of the antenna
    facing the house was tilted up a few degree's, the signal should have
    improved a little at least if indeed the problem you have is due to the AP
    being high up, also did you look for the cantenna information, this may well
    be a better bet for what you want.

    Dave, Nov 4, 2003
  5. Rich

    Rich Guest

    Hey Dave,

    Initially it didn't occur to me to adjust the angle - all I saw was a
    magnetic base mount and thought "huh, this must be right!".

    I'll have a play around with the angles and see what happens, then I'll post
    back with my findings.

    Also I looked for the Cantenna plans, there seem to be many variations,
    including the "Coffee Cantenna" and the "CookieCantenna" - but I think for
    me a standard Cantenna may do the trick. Of course, there's the point that I
    spent over £90 for all this stuff thinking it might work, and then I find a
    cantenna plan for free, and materials totalling no more than about $10 which
    could outperform my antenna altoghether .... Mmmmmm, how pleased am I?!

    So it's not a question of moving to a Cantenna, so much as making the
    antenna I bought work (and by the power of the Wi-Fi God it shall work!).

    I'm sure the equipment works fine, in the correct installation scenario.
    So --- I'll mess with the angles and see what results I get. If not good,
    I'll be building a Cantenna (quite a dodgy prospect since anything
    DIY-related invariably self-destructs when I DIY-it!), and this lot'll be
    finding it's way onto eBay!!!

    Cheers again,

    Rich, Nov 5, 2003
  6. Rich

    dold Guest

    The doughnut is probably not pointed in the right direction, as noted in
    the other posts in this thread. In addition to adding the external antenna
    to the laptop, you can cheaply add reflectors to the WAP, and point them
    as well as angle them. To view the optimum angles, what I did was to run
    VNCserver on the laptop, and VNCviewer on the dekstop, which was right near
    the WAP. Then I brought up the signal strength meter that came with the
    laptop adapter to monitor the signal while I repositioned the WAP and
    fiddled with the reflectors.

    dold, Nov 5, 2003
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