ADS-B DIY Antenna

Discussion in 'Antennas, Filters etc' started by Mukundan, May 3, 2013.

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  1. jepolch

    jepolch Active Member

    That's pretty bad. It's almost like buying a sugar free cake and reading on the label "This is not a low calorie food". :eek:
     
  2. ab cd

    ab cd Senior Member

    I think by "real loss" you mean the loss in components of the splitter.

    Let us take an ideal case of the splitter made of zero loss components. Even in this case, due to division of signal between two receivers, each of the two receivers will get 3dB less than if only one receiver was connected.

    In non-ideal case of 1.9 dB component loss, each of the two receiver will get 4.9dB less than what it will get if there was no splitter installed & only one receiver was connected to the antenna directly.
     
  3. giacomo1989

    giacomo1989 Member

    That's what I meant.
     
  4. jepolch

    jepolch Active Member

    ab cd, a while back you gave us a link to listen to live ATC comms. It had about a dozen links to ATC towers. Try this one. LOTS more towers to listen to: http://www.liveatc.net/
     
  5. ab cd

    ab cd Senior Member

    Wonderful! Thanks
     
  6. jepolch

    jepolch Active Member

    Here's a blast from the past - post #2! I'm curious how you use the input from the FM/Air-band whip with your SDR-RTL receiver. Thanks!
     
    ab cd likes this.
  7. ab cd

    ab cd Senior Member

    I used a software SDR# (SRD Sharp) to use my DVB-T USB Dongle to receive radio (FM/Air etc).
    SDR Sharp FM.PNG

    The DVB-T USB can be used either with the SDR# or with ADS-B Software.
    from one DVB-T USB you can't listen to Air Band as well as receive ADS-B signal simultaneously.
    For simultaneous use, you will need two DVB-T USBs, one for ADS-B, other for Air Band & FM.

    Here are the links for SDR#

    Software download:
    http://sdrsharp.com/#download

    Tutorials:

    (1) Quick Start Guide http://www.rtl-sdr.com/rtl-sdr-quick-start-guide/
    (2) Video Tutorial http://www.rtl-sdr.com/sdrsharp-video-tutorial/

    Another Tutorial:
    (DO NOT DOWNLOAD SOFTWARE FROM THIS SITE - LATEST VERSIONS ARE AVAILABLE FROM ABOVE NOTED ORIGINAL SITE)
    (1) Overview https://learn.adafruit.com/getting-started-with-rtl-sdr-and-sdr-sharp/overview
    (2) Download & Install https://learn.adafruit.com/getting-started-with-rtl-sdr-and-sdr-sharp/download-and-install-software
    (3) FM Radio https://learn.adafruit.com/getting-started-with-rtl-sdr-and-sdr-sharp/sdr-number-fm-radio
     
    Last edited: Dec 4, 2014
  8. jepolch

    jepolch Active Member

    That looks very interesting. When I saw both antennas attached to your dimuxer I got the impression you could process the input from both simultaneously. That would be cool. I will definitely be giving this a try when I have a spare DVB-T dongle available.

    Great news! I got the amp and connected it today. My reception increased somewhat, but not as much as I hoped. I was expecting up to 100% improvement. It's hard to say what I'm seeing, but maybe 20% more data? I had my highest number of positions reported and aircraft seen today, so it's definitely working.

    One thing that I've noticed is that I'm not seeing aircraft much more than 100nm from my location. I've got quite a few hits in the 100-150nm range according to my coverage stats, but I never see any aircraft out there, so I'm thinking they must barely cross the 100nm line. According to the circles on HeyWhatsThat I should be seeing planes a lot further out, I think. Anyway, things will be interesting when I put the antenna on the roof. I'm a little closer to that today. I went into my shed and got out the ladder I need to go onto the roof. I hope to have it finished within the week. :)

    Edit: I forgot to add that the coverage radius graph was done with an antenna height of 20 feet off the ground. My actual coverage is very close to the inner (orange) circle.
     

    Attached Files:

  9. ab cd

    ab cd Senior Member

    Two things are likely to improve range. Worth trying:

    (1) Raising antenna so that it is above roofs and trees. If antenna can see the horizon, you get the maximum range. Imagine your eyes in same place as the antenna. If your eyes see horizon, antenna alo sees horizon.

    (2) Move the amplifier closer to the antenna. Ideal location (from reception point of view) is between antenna and start of feeder coax, immediately below the antenn. This location is though not ideal from amplifier's protection point of view as the amplifier is designed for indoor use. If amplifier is inside an enclosure, or wrapped in self-amalgamating tape, it will overcome this issue, though summer heat will still be a problem. Ordinary Electrcal/PVC tape will not provide adequate rain/moisture peotection & will come out after some time.
     
    Last edited: Dec 5, 2014
  10. jepolch

    jepolch Active Member

    It's impossible to see the horizon from my location, due to all the trees. However, the area is pretty flat and I can't see any hills, so I probably COULD see the horizon while standing on top of my house if there were no trees.

    I'll attach the amp directly to the cantenna like you have yours when I move the antenna on top of the house. Both raising the antenna and moving the amp up there will probably help a lot. Right now the amp is at the opposite end of the coax from the antenna, closest to the receiver.

    The other day I was looking around the hardware section of Walmart (do you have Walmart in Canada?) and I was shocked to find self-amalgamating tape with the electrical tape. I was so surprised to see it I bought two rolls! I'll use that to seal the amp and other coax connections when I move the antenna.
     
  11. ab cd

    ab cd Senior Member

    Trees block microwave. Planes over 100nm are most probably blocked due to trees.

    If you put a mast at your roof top, raising antenna above trees, your range will increase to maximum (line of sight upto horizon) i.e. about 250 nm.

    heywhatsthat.com ignores man made structures (buildings) and trees. It takes into consideration only geological/geographical land features. That is why it showed much bigger range than you are getting.

    Your antenna & eyes do not ignore these features. Raising the antenna above tree-top level is the only solution to get full rang. Amplifier will not help much in this situation. The amplifier can boost weak signals from distance plane, but cannot re-create the signals blocked by obstructions such as trees & buildings.
     
    Last edited: Dec 5, 2014
  12. jepolch

    jepolch Active Member

    I guess that will always be a problem. The trees are up to 30 feet taller than my roof! But there are gaps between them, so I guess some signals will sneak through. Someday I might consider putting up a 40 foot tower, but right now it's not in my budget. I'll keep thinking about it. Fortunately our antennas are small, so there may be some lightweight pole I can rig up to get the antenna higher. I keep looking at the tallest trees in my front yard and wondering how I could get the antenna up near the top. Short of using a "cherry picker" I have no way of getting up that high!
     
  13. ab cd

    ab cd Senior Member

    This is so unfortunate! :(

    Light weight pole is a good idea. Even if you cannot go above tree top, any increase in antenna height will increse the range. Once you reach the tree top height, further increase wont help in increasing the range.

    Chop the trees down :D
    I remember electric company in our locality trimming the tree tops when these become too high and started touching the wires on power line.

    Or tie your antenna to a Helium filled Baloon floating above tree tops. :D
     
    Last edited: Dec 5, 2014
    giacomo1989 likes this.
  14. jepolch

    jepolch Active Member

    I'm sure everyone has some sort of antenna issue that's out of their control, right? I have WAY too many trees to cut down, plus I like the shade. Maybe I'll get a tall pole at some point, but remember, the point of putting the antenna on the roof is because the house is blocking my reception to the east. I have pretty good reception in other directions. So just putting it on the roof will be a plus. :)
    I may do it today, but it's not looking good. I have to go out for some screws and other small stuff. By the time I get back I may not feel like going up on the roof! I should have gotten an earlier start!
     
  15. giacomo1989

    giacomo1989 Member

    Hey abcd my cantenna is done :) I haven't cutted the can yet so it's not perfectly balanced but seems to work better than my 6 elemetn CoCo in the same position!!!!!

    It's not even well centered :)
    I'll attach the coverage pattern as soon it's builds up :)
    What do you think? :)
    IMG_20141206_142501.jpg
     
  16. ab cd

    ab cd Senior Member

    Looks nice!
    Congratulations.
     
    giacomo1989 likes this.
  17. giacomo1989

    giacomo1989 Member

    Antenna pattern inside the house :)

    Schermata del 2014-12-07 12:09:59.png

    Damn mountains :)
     
  18. ab cd

    ab cd Senior Member

    This is so unfortunate! No solution to mountain problem. :(

    I don't have mountains, but have many high-rise buildings around, which restrict my range in their directions.

    My own building is worst. It blocks nearly half (180 degrees) view out of full view (360 degrees)! :(
     
  19. jepolch

    jepolch Active Member

    You guys need helium balloons! ;)

    Giacomo how did you plot that antenna pattern?
     
  20. ab cd

    ab cd Senior Member

    Tit for tat! You put a Trump card over my Ace :D
     
    Last edited: Dec 8, 2014
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