I only want to go 500 feet (outdoors), but can't quite get to 150 feet.

Discussion in 'Wireless Internet' started by Dave M, Jun 30, 2004.

  1. Dave M

    Dave M Guest

    I would appreciate some help understanding what I have done wrong here. I am
    attempting to extend access out to a gazebo about 500-600 feet from my main
    location.

    My set-up consists of
    DLink MI-514 Wireless Router
    about 20' of LMR 400 antenna cable
    A 8.5 dB Omnidirectional Antenna (no downtilt to the radiation pattern)
    A Dell Laptop with a built-in True Mobile card.
    Assorted pigtails, adapters, and lighting arrestor.

    I mounted the antenna outside the main location about 3' from the ground,
    and I have unobstructed LOS to the gazebo.

    I thought that this would be a slam-dunk, as the advertised range of the
    DI-514 is 300 feet indoors and 1300 feet outdoors (yes, I realize under
    "ideal" conditions). I thought putting the antenna outside in direct LOS of
    the gazebo would pretty much make the conditions as ideal as possible, as
    well as increase the gain in the system.

    I estimated the signal strength close to the antenna (accounting for cable
    loss, antenna gain, and free space loss) at about
    -13dBm.
    OK, I ignored any losses in the assorted pigtails, etc..

    Using the utilities shipped with my laptop, the received signal levels I
    experience are as follows:

    at 5 to 10 feet -27 dBm
    at 50 feet -50 dBm
    at 100 feet -61 dBm
    at 150 feet -73 dBm

    At each location, I am in full view of the antenna. Beyond 150 feet I can't
    hold the signal long enough to get a good reading.

    The annoying aspect is that for some reason I can also pick up another
    wireless network at all locations, although not reliably. When I can get a
    signal from the other network, it appears to be in the -60 dBm to -70 dBm
    range. The signal strength is pretty independent of where I am along the
    path to the gazebo. In other words, the signal strength from the other
    network is stronger in some locations in others, but not clearly stronger at
    one end or the other of the path to the gazebo. (I haven't determined which
    neighbors signal I have yet, but suspect that a line to their location is
    perpendicular to the path to the gazebo.)

    Any thoughts??

    Dave M
     
    Dave M, Jun 30, 2004
    #1
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  2. Dave M

    bumtracks Guest

    think 3' is awfully close to the grnd, might raise it up and see if things
    improve .
    fwiw
    I've a di624 with both a 5.5db omni range extender and a 6db 80degree
    directional panel attached and with a standard g pc card - at 150' signal
    is around half strength on the little indicators.

    I'm no antenna guru, but when I added a 8db yaggi directional flag antenna
    to the laptops compex g pc.card it was a definite grin maker. It's 100%
    signal most anywhere ,,, one bad area that was 26% is now 76% aimed through
    I guess mortar over wire lath wall and two other wood/drywall type sidings.
     
    bumtracks, Jul 1, 2004
    #2
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  3. Dave M

    f/f george Guest

    I would have to agree, 3' is awfully close to go that distance. The
    other thing you might try is getting a stronger antenna and see if
    that helps. Myabe buy it, try it, if it doesn't help take it
    back...think Radio Shack, Circuit city, etc.
    A somewhat trial and error thing to try is putting up a small(12"x12")
    piece of cardboard covered with aluminum foil to act as a reflector
    behind your current antenna and see if the numbers get better. I have
    seen this work indoors so a stainless metal panel would work outdoors.
    Smooth out the foil as much as you can.
     
    f/f george, Jul 1, 2004
    #3
  4. Dave M

    Ron Bandes Guest

    Do you know what channels your neighbors' signals are using? Try to find a
    channel away from theirs.

    Ron Bandes, CCNP, CTT+, etc.
     
    Ron Bandes, Jul 1, 2004
    #4
  5. What specific antenna did you add?
     
    brian-s-jones-at-comcast.net, Jul 1, 2004
    #5
  6. Dave M

    Lucas Tam Guest

    Buy a larger Antenna.
     
    Lucas Tam, Jul 1, 2004
    #6
  7. Dave M

    Phil Schuman Guest

    yeah - those published numbers are always interesting -
    I've wanted to take my WAP11 Access Point and do a test in a local soccer
    field -

    Take my UPS and a couple of laptops - for a small network setup -
    Setup the WAP11 and a laptop connected via hub - with the UPS for power
    Then take another laptop and do a walk around site survey -
    It would be real interesting to see some results from this kind of test...
    Wonder if anyone has done this - and posted it to the web ?
    Phil
     
    Phil Schuman, Jul 2, 2004
    #7
  8. Dave M

    dold Guest

    dold, Jul 2, 2004
    #8
  9. Dave M

    bumtracks Guest

    bumtracks, Jul 2, 2004
    #9
  10. Dave M

    JT Guest

     
    JT, Jul 4, 2004
    #10
  11. I am no guru, but as soon as I read your post, It is my best opinion that
    you need to raise your antenna. Put it as high as possible. I have always
    read that your antenna needs to be high as possible.

    Hope this helps.

    Jason
     
    Jason Arredondo, Jul 4, 2004
    #11
  12. This should be a no-brainer with LOTS of signal to play with. In
    other words, it should work without difficulties.

    The DI-514 has an R-SMA connector for the antenna. However, the
    thickness of the plastic rear panel, lock washer, and SMA nut all
    accumulate to cause a typical R-SMA connector to NOT fit very well.
    My guess(tm) is that the center pin is not making very good contact.
    Unscrew the gold nut, remove the lockwasher, and put the nut back and
    it will work. (Note: This drove me nuts for a few hours until I
    discovered the problem).
    My guess(tm) is that you have too much antenna gain. An 8.5dBi omni
    antenna will have a -3dB vertical beamwidth of about 10 degrees. That
    means that the bulk of your power goes into an area that is plus or
    minus 5 degrees from horizontal. Actually, there may be some uptilt
    in the pattern if the antenna is mounted close to a horizontal ground
    plane.

    At 500ft trigonometry proclaims that a 10 degree beamwidth results in
    a useful vertical coverage area of perhaps plus or minus 44 ft. If
    the antenna was mounted on a tall rooftop, and your laptop is at
    ground level, you're sending most of your RF over your laptops head.
    Of course, you could tilt the antenna over towards the gazeebo, that
    would be aesthetically disgusting.
    Yeah, that's about what I would expect from sending the signal over
    your head.
     
    Jeff Liebermann, Jul 4, 2004
    #12
  13. Dave M

    hellbound Guest

    your built in dell notebook is not good
    there is no good antenna for notebook and they usually use intel base
    chipset with poor RF power and bad ceramic antenna

    I had same problem as yours
    I tried one USB wireless from dlink and I am going up to 1.3 KM (430
    feet) and having up to 11 megabit in most of place with line of sight.


    but my antenna is at the 21st level of building located on very hig
    mountain


    hope it help
     
    hellbound, Jul 6, 2004
    #13
  14. Dave M

    Dave M Guest

    I appreciate all the comments that have been made. I will try some of the
    suggestions provided and let you know what I find out.

    Thanks Again,
    Dave.
     
    Dave M, Jul 7, 2004
    #14
  15. Dave M

    K Bloch Guest

    If that doesn't work try not using an omni antenna and use a flat
    panel like the andrew 11 dbi model dl2412. These offer a much higher
    beamwidth of 75 x 27 degrees. The beamwidth can be changed either
    vertical or horizontal depending on how it is mounted.

    As people said with the omni the beamwidth is very narrow so if you
    are just above or below the beamwidth you will very little signal.

    Also generally as you double the distance your signal should drop by 6
    db. If it is dropping by more than this amount you are not in the main
    beam but likely in a side lobe.
     
    K Bloch, Jul 8, 2004
    #15
  16. Sounds like you either have put bad ends on your cable, have bad cable, or
    a bad antenna.

    MI-514 output: 15dbm - about 5db for the LMR400 run = 10dbm -1db for
    connectors=9dbm
    +8.5db for the antenna (by the way.. place this high.. an omni at this high
    a gain will have a super
    tight angle of radiation.. probably a lower gain antenna at that height
    would be better) = 17.5dbm
    At 17.5dbm EIRP you should yield a much higher RSSI at the distances you
    list...

    Your 20 ft of LMR400 is also hurting you as LMR400 has a huge loss/ft
    By moving to LMR600 you will probably gain about 3dbi which will double your
    output power/rcvr
    power... But again.. check all your connections as I bet it is just a bad
    antenna connector..
    Check with an ohm meter for impedence as well 52ohms
     
    Fresnel Fadermargini, Jul 10, 2004
    #16
  17. Dave M

    xray Guest

    That is bad advice. The 50 ohm thing is an RF impedance. An ohm meter
    will never measure it unless something might just happen to be
    terminated with a 50 ohm resistor -- unlikely.

    The idea to check with an ohm meter is fine, but it is just a continuity
    / short test. If you get the two ends of the cable in one place, check
    to make sure the grounds (shield side) of both ends are connected. The
    center wires are connected, and there is no short between the shield and
    center (one end should be fine, but try both if it makes you feel
    better).

    Measuring the impedence, which could affect transmission through SWR
    reflections, or the loss at 2.4 GHz, is not something you can do with an
    ohm meter, but if you used proper cable and connectors, and the ohm
    meter continuity/short tests are ok, then it is unlikely you need to
    make any other tests which would require special RF test equipment.

    Just wanted to get some reality here and not have you thinking there
    should be 50 ohms you can measure with an DC ohm meter.
     
    xray, Jul 10, 2004
    #17
  18. Dave M

    tony sayer Guest

    Your 20 ft of LMR400 is also hurting you as LMR400 has a huge loss/ft
    How can you measure impedance with an ohmmeter at these frequencies?..
     
    tony sayer, Jul 10, 2004
    #18
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