any comments? any ideas?

Discussion in 'Wireless Internet' started by Guest, Jul 16, 2005.

  1. Guest

    Guest Guest

    I have setup a 802.11b wireless bridge between two buildings - use the first
    generation Linksys WAP11 access points (the ones with the USB port).

    - I used the hack and boosted the signal to 100% on each.
    - The one unit is sitting in a basement window. The antenna's were replaced
    with the radio shack 6db "duck" ones.
    - The other unit is sitting below a window on a shelf, and I put a single
    Hawking "high gain 6db" on it ...because it had a 2 ft cable - allowing me
    to put it antenna on the sill.
    - The two have clear line of site and are about 75' apart

    Everything worked great for 2 years. Now the interesting part......

    The one building had the windows replaced with new Andersen windows. That's
    the window with the 10" high Hawking H-AI6SIP antenna
    (http://www.amazon.com/exec/obidos/ASIN/B0000ABPKG/ref=pd_sxp_elt_l1/104-9160163-9816714)
    .. The bridge now would no longer work. When the window was open - it
    worked. When the window was closed, it would not. FYI - the original
    window was a standard wood frame, single pane of glass, not metal or
    plastic - all wood window.

    I was going to look at getting an outside antenna and run a wire into the
    house, etc .... but I had a spare Belkin F5D6900 antenna
    (http://www.amazon.com/exec/obidos/t..._f/104-9160163-9816714?v=glance&s=electronics)
    that is supposed to be used with a PCI desktop card. It is much shorter -
    about 3 inches high and just clears the bottom part of the window frame.
    The Belkin antenna is not a "high gain" antenna.

    Once I swapped the Hawking with the Belkin - the connection re-established
    and all is well - when the window is open and closed.

    Anyone have any ideas on why it ..

    1) the Andersen window blocked the signal, and

    2) why the Belkin antenna worked when the Hawking would not?

    --
     
    Guest, Jul 16, 2005
    #1
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  2. Guest

    NotMe Guest

    <riggor9999>
    | I have setup a 802.11b wireless bridge between two buildings - use the
    first
    | generation Linksys WAP11 access points (the ones with the USB port).
    |
    | - I used the hack and boosted the signal to 100% on each.
    | - The one unit is sitting in a basement window. The antenna's were
    replaced
    | with the radio shack 6db "duck" ones.
    | - The other unit is sitting below a window on a shelf, and I put a single
    | Hawking "high gain 6db" on it ...because it had a 2 ft cable - allowing me
    | to put it antenna on the sill.
    | - The two have clear line of site and are about 75' apart
    |
    | Everything worked great for 2 years. Now the interesting part......
    |
    | The one building had the windows replaced with new Andersen windows.
    That's
    | the window with the 10" high Hawking H-AI6SIP antenna
    |
    (http://www.amazon.com/exec/obidos/ASIN/B0000ABPKG/ref=pd_sxp_elt_l1/104-916
    0163-9816714)
    | . The bridge now would no longer work. When the window was open - it
    | worked. When the window was closed, it would not. FYI - the original
    | window was a standard wood frame, single pane of glass, not metal or
    | plastic - all wood window.
    |
    | I was going to look at getting an outside antenna and run a wire into the
    | house, etc .... but I had a spare Belkin F5D6900 antenna
    |
    (http://www.amazon.com/exec/obidos/tg/detail/-/B00006SCIX/ref=pd_sxp_f/104-9
    160163-9816714?v=glance&s=electronics)
    | that is supposed to be used with a PCI desktop card. It is much shorter -
    | about 3 inches high and just clears the bottom part of the window frame.
    | The Belkin antenna is not a "high gain" antenna.
    |
    | Once I swapped the Hawking with the Belkin - the connection re-established
    | and all is well - when the window is open and closed.
    |
    | Anyone have any ideas on why it ..
    |
    | 1) the Andersen window blocked the signal, and
    |
    | 2) why the Belkin antenna worked when the Hawking would not?
    |
    |

    1 the Andersen windows likely have a metalized thermal insulation.

    2 the link budget on the hawking was lower the belkin and in the original
    case made no difference (like the military definition of rape 'penetration
    however slight is sufficient to complete the act"
     
    NotMe, Jul 17, 2005
    #2
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  3. I have about 5 of those pieces of junk in a pile somewhere. They were
    the first cheap transparent bridge radios in their day. After about 5
    major revisions of the Atmel firmware, and the pieces of junk were
    still locking up all the time, I gave up on them. I'm glad you got
    them working.

    Incidentally 1.0 and 1.1 had the USB port. 2.2, 2.6 and 2.8 did not
    have the USB port. 1.0 was junk. 1.1 is improved junk that didn't
    lockup as much. 2.2 and above are fine.
    Good for you. I wonder if the FCC offers a reward for turning in
    spectrum polluters? The problem is that cranking up the power beyond
    the rated and tested levels causes the tx amplifier to spray garbage
    beyond the typical 26MHz of occupied bandwidth for 802.11b. It also
    creates amplitude (envelope) distortion which severely affects the
    ability of the receiver to extract the data. You may crank out more
    RF, but how much of it is in the receiver bandpass, and how much of it
    can be used by the receiver is questionable.

    As I recall, the WAP11 running DWL-900AP+ firmware, which is what I
    guess you were doing, doesn't really increase the tx power enough to
    cause a problem. However, if you find that you are running a system
    sufficiently marginal that you need the extra power, methinks you
    should look instead for a better antenna pair or better line of sight,
    as such a marginal system is sure to eventually fail when something
    changes.
    Are the at the same vertical elevation? If not, the omni antennas
    should be parallel to each other for best performance. I would NOT
    use omni antennas for such a point to point link. The WAP11's have
    RP-TNC connectors and decent antennas are easy to build or buy. My
    version of the common biquad in an outdoor box:
    http://802.11junk.com/jeffl/pics/antennas/biquad2/
    6dBi of antenna gain (maybe) with about 3ft of RG-316 for a loss of
    1dB. Net gain is about 5dBi if you ignore connector and adapter
    losses.
    It's difficult to tell without seeing the window. Many windows have a
    sputtered aluminium coating to improve insulation qualities. Most
    double pane windows do this. Blocks RF quite nicely. The new science
    building at the local university (UCSC) has windows almost impervious
    to RF which is causing problems using cell phones inside the building.

    Another possiblity is a vertical difference in elevation as I
    previously asked. The Hawking antenna tend to radiate most of its RF
    near the base of the antenna. If the base was partially obstructed by
    a metal frame window, then you will have some signal loss. Similarly,
    the wooden frame window will pass more RF throught the wooden frame.
    I'm not sure I would even call it an antenna. Zero specifications on
    the Belkin web pile. No clue as to the gain, length of cable, or type
    of cable. My guess is a simple vertical coaxial antenna with a
    theoretical gain of 2dBi, perhaps 3ft of cheap non-PTFE coax for a
    loss of about 1.6dB, with a net gain of 0.4dBi. Don't bother.

    What part of the antenna "just clears" the window frame? This is
    critical as the entire antenna, including parts of the base, must
    clear the window frame. If not, and you get too close to the metal
    frame, you end up detuneing the antenna, creating VSWR, havoc, etc.
    Well, I'm suprised as I would think the Hawking antenna would have
    more gain than the Belkin. Elevation difference (tilt angle) again?
    Metal frame instead of wood. Aluminium sputtered coating.
    Dunno. Many such antennas have a tendency to place much of their RF
    in the upwards direction. Uptilt is more of a problem with high gain
    omni antennas, where you could easily send the signal over everyone's
    heads or to the sky instead of the ground. However, on all counts, I
    would have expected the Belkin antenna to be far worse than the
    Hawking. Assuming everything is working properly, I'm guessing that
    you have a really marginal link, where any small changes in position
    or antenna location will cause difficult to predict changes in antenna
    patterns. For example, reflections from the window frames or other
    objects in the path. Is your system *VERY* sensitive to exact antenna
    location?

    However, you're doing this all wrong. Omni antennas are not a good
    idea for a point to point link. Use directional gain antennas. Even
    two coffee can antennas would be a major improvement. Coffee can
    antennas are about 8dBi gain. Single panel antennas are about the
    same. Biquad's can go up to 10dBi gain. Assuming your existing pair
    of omnis each has a gain of 2dBi, a pair of biquads will yield a 16dBi
    increase in fade margin, which is a *HUGE* improvement. Maybe then
    you might turn down the RF power to normal levels and not trash the
    neighborhood.
     
    Jeff Liebermann, Jul 17, 2005
    #3
  4. Guest

    riggor99999 Guest

    To answer your questions / address your concerns:

    - I am using several of the Linksys WAP11 ver 1.1 without any problems at
    all. I have been for years.

    - I realize this is not a perfect setup / not optimal....but this is a
    light use / occasional use link. Not a commercial use / link. I set it up
    with what I had on hand - trying not to spend any extra time or money. Just
    put the units behind some windows / curtains, and tried not to be and eye
    sore.

    - The link is not and has not been sensitive to antenna placement at all.
    The antenna sits on a window sill and is moved every so often for various
    reasons.

    - I used the Atmel utilities to increase the power
    (http://www.seattlewireless.net/index.cgi/Wap11Hack) - not the D-Link
    firmware hack.

    - I have NEVER had a problem with this bridge in 2 years. All this started
    when the windows were replaced - the antenna and signal strength and
    connection was ALWAYS rock solid before the windows were changed.

    - I got the all omni antennas for free - and since they are on 75 feet with
    clear line of site - I don't think it matters for this short distance ...
    omni versus directional.

    - The window I am talking about with the Hawking / Belkin antenna is about
    4 feet higher than the other WAP11 unit with the Radio Shack
    antenna.....with a 75 foot clear line of sight distance.

    - Once the Hawking stopped working with the window closed - I figured I
    would get a directional outdoor antenna, or put the antennas outside is some
    sort of weather proof case. I had the Belkin so I tried it just for grins.
    It worked. I am good.

    - The Hawking antenna (including the base) clears the window frame. Only
    the top 1.5 inch of the Belkin antenna now clears the frame.

    - It's now working - no drop offs, no signal loss. I have been running
    continuous ping tests, data transfer tests, etc - all is solid. I am not
    going to chase this down anymore since it's working. Clearly opening and
    closing the window would break the connection when the cheap Hawking antenna
    was at the window. The Belkin stays up with the window closed. That's all
    I wanted.

    - The Belkin is not supposed to be a high gain antenna - but just an
    antenna to a desktop PCI card. It has about 3 foot of wire between the
    antenna to the Linksys unit, compared to the 2 foot wire of the Belkin.

    - This setup is in the middle of nowhere - no neighbors - no wireless
    pollution affecting anyone. Thanks for your concern.

    - These are setup as point to point bridge, so they can only talk to each
    other's MAC address. SSID broadcast is off and WEP 128 is on.

    - The post was to try to figure out the RF and window issues, and why in
    theory, a sub-optimal the Belkin el cheapo antenna is working better than
    the original Hawking el cheapo "high gain" antenna...not a plea for how to
    setup a better directional link. The only reason I went that way is because
    I did not have the space to put the Linksys on the sill...so I put the unit
    near the window and used an antenna that would sit on the sill.
     
    riggor99999, Jul 17, 2005
    #4
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