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Thread: best antenna

  1. #2641
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    Thank you Sir. I shall set aside my worries of mismatched connectors. In truth I actually knew all that but, I did not know that I knew it. I learned it back in the 1960s when I was an university. I am now 71 so the emotional attachment remains (impedance mismatched are bad, bad, bad) but the math had leeched away over the decades.

    I am just about to move my RPis up to the attic. The plan is to use CAT5 cable for the long cable run (21ft, 7 meters) instead of RG6. Just about to drill the hole and climb the ladder into the attic. Once I have all that stable and a couple of days of statistics down I will look again at which antenna I am going to use. I built a Franklin the other day but my LNAs are scattered in the snail mail cloud so I shall have to wait before testing. More news later.
    20170218_130504.jpg
    Last edited by rederikus; 2017-02-18 at 18:25.

  2. #2642
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    Now that I can post links, this is where I found the dump1090 command line parameters. http://www.satsignal.eu/raspberry-pi...tml#parameters

    The source for the above link ws found here http://planeplotter.pbworks.com/w/pa...95023/Dump1090. You need to look down the page to the "Known Issues" paragraph.

  3. #2643
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    Your Franklin is nicely built.

    Did the integral dump1090 of FR24 feeder accept --gain <db> command directly from SSH window?
    In my case it did not. If yes, can you please post the full command?
    I used following two commands, but these did not work:
    (1) pi@raspberrypi:~$ sudo /usr/lib/fr24/ ./dump1090 --gain 32.8
    (2) pi@raspberrypi:~$ sudo fr24feed --gain 32.8

    Finally I entered the argument --gain <db> in settings page http://<IP of Pi>:8754/settings.html and it worked.

  4. #2644
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    Yes, the gain command worked just fine thanks. Like you I have been unable to make any Linux command line gain changes. They work fine from the Settings page of the RPi webpage http://<ip address of my rpi>:8754/settings.html. I have mirrored your text in the interests of clarity. You probably saw my earlier post of a list of Dump1090 commands. These seems to do something when entered from the Settings page. --aggressive increases CPU load on an RPi2 to about 45-50% and scarcely at all on an RPi3. I saw no increase in range using this command switch.

    My Franklin is your design with 138mm elements. I used 8AWG (2.26mm dia, Home Depot or Lowes grounding wire) and soldered the U bends. I used my grindstone to reduce the thickness of the copper wire by about 50% so that I could use a single right angle bend on each U bend wire. This made soldering easy. I just clamped the U bend in my vise, bent the wire so they pushed against each other and used a small propane torch to heat it up. It works but only give me about 85nmi with the ProStick gain at 50. When I get my LNAs I shall shorten the feeder and put the first LAN co-located with the antenna.

    Once I have my LAN working in the attic (the CAT5 is up there now) and all the electrics and electronics is neatly inside the NEMA steel box my insurance company insist on I will be able to run KCLT3 with 2 foot feeder in place of my current 21 ft RG6 feeder. Then it will be LNA and musical antenna time again. Hehe.

    Thanks again for your help. This thread is a mine of information -- some of it useful
    Last edited by rederikus; 2017-02-18 at 19:59.

  5. #2645
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    Quote Originally Posted by rederikus View Post
    Thank you Sir. I shall set aside my worries of mismatched connectors. In truth I actually knew all that but, I did not know that I knew it. I learned it back in the 1960s when I was an university. I am now 71 so the emotional attachment remains (impedance mismatched are bad, bad, bad) but the math had leeched away over the decades.
    I am glad to meet a seasoned University Graduate in Electrical Engineering.


    Quote Originally Posted by rederikus View Post
    I am just about to move my RPis up to the attic. The plan is to use CAT5 cable for the long cable run (21ft, 7 meters) instead of RG6. Just about to drill the hole and climb the ladder into the attic. Once I have all that stable and a couple of days of statistics down I will look again at which antenna I am going to use. I built a Franklin the other day but my LNAs are scattered in the snail mail cloud so I shall have to wait before testing. More news later.
    20170218_130504.jpg
    After trying so many wire co-linear antennas, all of which performed less than or equal to a 1/4 wavelength ground plane antenna (Spider & Cantenna), I have come to conclusion that for begginers, the most suitable and easy DIY antennas are Spider & Cantenna.

    Below is photo of some of my failed wire collinears which I found in my spare & scraps drawer. There were lot more, but have ended up in trash.


    ALL THESES FAILED!

  6. #2646
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    Hi abcd567,

    With my set up,I have my antenne, 3metres above the roof,. Connect to 5 metres of Low loss Co-axial(Expensive) to the Reciever (In the Attic).
    Then from the Reciever connected to the power supply using a Dlink,. To my Router downstairs,.. which saves all the drilling and laying of cables.

    The catch is,... That both Sockets must be on the same circuit...
    (F-EDLE1)delcomp-DEL-David Tks(My friend Mike, all three of them)

    URL: http://banner.flightdiary.net/EDLM
    1090SJ(Ae) /(6m. Ecoflex10) / SBS 3 /-FR24 Box/ Power-line Connection (Ethernet)

  7. #2647
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    @adsb567 I have not failed. I've just found 10,000 ways that won't work. Thomas Edison. What you and your research has shown is what does not work as you thought and you have identified at least two ways that do work.

    I have read through all 265 pages of this thread and I'm trying to take your best working efforts and apply them myself.

    The problem is that the only reference antenna I have is the little whip thing that came with my first USB stick receiver. I make a new antenna and stick it up. If it gives me more range I keep it. Otherwise i bin it.

    To this end I am considering buying a DPD Productions ADS-B Vertical Outdoor Base Antenna http://www.dpdproductions.com/page_vhf_air.html#adsbout This claims 9dBi gain so it is probably better than anything I can build. Once this is installed (I cannot have an external antenna where I live) I can see if I can build one that's better.

  8. #2648
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    @rederikus
    Try these easy things to improve reception (if not yet tried)

    1. IMPROVE WHIP (Click Here)
      1. Place the whip antenna (which came with DVB-T USB Stick) on a large food can or metallic plate to provide a ground plane. The tin can/plate has an added advantage that the magnetic base of whip clings to it, preventing whip from falling and keeps it upright.
      2. Cut whip to 52mm (removable part)

    2. MAKE A CANTENNA (Click Here)

    3. MAKE A HANDY SPIDER (Click Here)

  9. #2649
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    Quote Originally Posted by rederikus View Post
    @adsb567 [B]

    To this end I am considering buying a DPD Productions ADS-B Vertical Outdoor Base Antenna http://www.dpdproductions.com/page_vhf_air.html#adsbout This claims 9dBi gain so it is probably better than anything I can build. Once this is installed (I cannot have an external antenna where I live) I can see if I can build one that's better.
    Don't forget that these and similar antenna require a large area of free space around them, at least 3 feet (1 meter) otherwise their resonant frequency will be shifted significantly and the reception will be seriously compromised.
    These are far better suited to exterior mounting, if this is not possible then an empty attic is sometimes acceptable, any nearby walls or metal structures will not only attenuate the signal but could also badly detune the antenna.
    FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

  10. #2650
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    @F-EGLF1, Good advice. Antenna calculations are done assuming free air and if the installation does not reflect this then performance usually suffers. I would love to site my antenna outside but it is just not possible due to the local housing association regulations. When I lived in Reading, UK we had a nice empty loft (known as an attic over here). However in the US the attic is used to house the HVAC (Heating Ventilation Air Conditioning) unit. This is a combined ducted air furnace and a huge air-conditioner for the whole house. This device is mostly made of metal. Additionally there are air ducts that have wire wound interiors to move the air around. It is a challenge to achieve 1 metre of clear air around the antenna.

    @abcd567, I built a spider 20161231_115359.jpg It did not work very well. I also built a cantenna using the large can of tomatos design. I found that the ground wire of the coax was not connected to the magnetic base of the whip antenna. Once I fixed this performance improved but was not a good as I wanted. My 8 element CoCo seems much better. I now believe that I am never going to get much better performance than I have today. I base this on a HeyWhatsThat panorama HeyWhatThat.jpg I'm near the bottom of a hole here. What HeyWhatsThat shows is pretty much what dump1090 shows dump1090.jpg. This combined with my Polar Plot stats.JPG (8 element CoCo) all seem to show that I am getting about as much range as I can hope for. Almost wherever I look, There are hills in the way AzEl.JPG

    Obviously I shall try and improve things but based upon my research, I am not hopeful. My station T-KCLT3 is currently number 2 in Charlotte according to FLightRadar24's coverage. I do not expect this to last as there is F-KCLT2 station who can see far further than me.
    Last edited by rederikus; 2017-02-20 at 20:57.
    T-KCLT3 - Raspberry Pi3 Jessie, 8 element collinear indoor antenna

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