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  • Originally posted by charan View Post
    yes i can but the only problem is if i increased the height of the antenna there is lot of noise building up i donno what to do for that.. someone stated that as EMF and suggested a static bag to cover the dongle but it didn't help can you suggest me anything to finish the top? thanks
    Originally posted by FRC View Post
    Hello everyone,

    im just following this tread a while and my doubt is about interferences near 1090Mhz.
    I just built an antenna from this site: http://www.qsl.net/py4zbz/adsb.htm#b similar to one described earlier.
    [ATTACH=CONFIG]3860[/ATTACH]

    What a newbie can do to solve this.

    Thx.

    Marcelo.
    Have a look at http://adsb.alle.bg/filter/ for designs of antenna filters. [this doesn't look easy!]

    Comment


    • Originally posted by peterhr View Post
      So this was the post that started this discussion - who would like to extract the info and start the new threads (Ideally abdc567 since that the is member who has done most work on this) - others then can add detail on improvements. How to build and how to best connect to a dongle. People who buy commercial receivers as a startup are more likely to buy a commercial antenna and not be in the DIY world.

      I'd like to encourage first antennas to bamboo poles etc so users can tweak them before sealing them into PVC / fibreglass tubes ... admitted an unsealed antenna attached to bamboo in the wet is not ideal.
      @peterhr @abdc567 @ those I can't remember but been a big contribution to this Thread

      I think it's a very good idea to make a separate Thread called "DIY- antennas RESULTS"
      But that Thread should be closed and only be accessed by one or two members to update the results. If not, you're just going to duplicate and end up with the same "problem"

      I've been reading 80+ pages of this Thread and many posts are very interessting, and others not so much, even if they somehow contribute to the discussions.
      I'm hoping to post my results soon here with some tips for particular problems I encountered and how I dealted with them.
      I didn't do any inventions, I just applied different tips of different people here in this Thread.
      But I've would have safed myself a lot of time if there would have been a "Results" thread even if following the different discussions is also very rewarding and helpful.
      So I guess this "Results" Thread could be a quick start for those who want to venture in their first DIY antenna, after that they will go to the "Discussion" Thread anyway to learn more about it.
      Well, just my opinion and again, thanks to all contributers, it is a very interesting and educating Thread

      Cheers

      Comment


      • when your using that software you will need a aircraft overhead broadcasting, if theres nothing there to listen too you will hear nothing. if that makes sense.


        I recently built one of the aerials you have just made this is the plot from adsb scope from about 17:00 hours yesterday to about now, when iswapped it over to a colinear aerial.
        wire.jpg

        this is a respectble range, i now have the colinear up in the same place i will post the results tomorrow.
        Last edited by SpaxmoidJAm; 2014-04-12, 09:26.
        T-EGLF8

        Comment


        • My range from the 8 element CoCo (with 68mm spike on the top) design, which has been in place for over two weeks.
          Screen Shot 2014-04-12 at 10.35.01 PM.png
          http://goo.gl/maps/U33Yb

          DSC_0197 copy.jpg
          F-YSWG1 and T-YSWG2

          Comment


          • Originally posted by charan View Post
            someone stated that as EMF and suggested a static bag to cover the dongle but it didn't help
            Only useful if the dongle is getting EMF (the only thing shielding it is a plastic case) from something near by (PC, power point, monitor, tv ect) but it can't stop any EMF or any other interference (internal or external) entering via the antenna or the cable from antenna to the dongle.
            F-YSWG1 and T-YSWG2

            Comment


            • Originally posted by peterhr View Post
              Have a look at http://adsb.alle.bg/filter/ for designs of antenna filters. [this doesn't look easy!]
              This is beyond my knowledge. This threat is about low cost and easy to build antennas. That filters are too complicated.
              Is there other solutions ? Something simple and low cost ?

              Comment


              • Originally posted by FRC View Post
                This is beyond my knowledge. This threat is about low cost and easy to build antennas. That filters are too complicated.
                Is there other solutions ? Something simple and low cost ?
                Agreed - too complicated

                Comment


                • Whilst this thread is interesting and informative it is difficult for a newcomer to separate what is needed to build your own antenna.
                  I'm a newcomer and I find the maths/technical stuff interesting but I would never pick up a book called something like "The theory of antenna design". The technical contributions are relevant to the designs being discussed. I'm not sure how the thread could be split.

                  Just stick with it, bend some wire and re-read the bits you don't understand.
                  Last edited by trigger; 2014-04-12, 20:52.
                  T-EGUB1

                  Comment


                  • I think a little bit further down the road we should make a new thread get some good links to aerial builds early on, so when new people come on and want to build there own they can find the information easily at 80 odd pages theres a lot to sift through.


                    on a side note my colinear isnt doing very well if i get a moment tomorrow i'll see if i can rebuild it.
                    Last edited by SpaxmoidJAm; 2014-04-12, 21:41.
                    T-EGLF8

                    Comment


                    • the filter is too complicated
                      RTL SDR : T-VEVZ1

                      Comment


                      • Computer Simulation of 3, 4, 6, & 8 Element Coaxial Collinear Antennas

                        I have done computer simulations for above CoCos, and results are shown in screenshots below.
                        I have used air insulated model to avoid assumption of Velocity Factor.

                        SCREENSHOT 1 of 4 - Three (3) Element CoCo
                        Gain = 3.26 dBi, SWR = 14.2 (mismatch loss = 6.1 dB)
                        Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 3.26 - 6.1 = -2.84 dBi
                        coco 3 element simulation output.png



                        SCREENSHOT 2 of 4 - Four (4) Element CoCo
                        Gain = 6.87 dBi, SWR = 8.98 (mismatch loss = 4.43 dB)
                        Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 6.87 - 4.43 = 2.44 dBi
                        coco 4 element simulation output.png



                        SCREENSHOT 3 of 4 - Six (6) Element CoCo
                        Gain = 8.42 dBi, SWR = 5.86 (mismatch loss = 3.03 dB)
                        Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 8.42 - 3.03 = 5.39 dBi
                        coco 6 element simulation output.png



                        SCREENSHOT 4 of 4 - Eight (8) Element CoCo
                        Gain = 9.52 dBi, SWR = 4.63 (mismatch loss = 2.33 dB)
                        Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 9.52 - 2.33 = 7.19 dBi
                        coco 8 element simulation output.png
                        Last edited by abcd567; 2014-04-14, 08:08.

                        Comment


                        • Originally posted by SpaxmoidJAm View Post
                          I think a little bit further down the road we should make a new thread get some good links to aerial builds early on, so when new people come on and want to build there own they can find the information easily at 80 odd pages theres a lot to sift through.


                          on a side note my colinear isnt doing very well if i get a moment tomorrow i'll see if i can rebuild it.
                          Actually another solution to separate and keep everything together at the same time is that whenever there's a tested antenna build the first post in this Thread is updated with that information.
                          In that way you will have a nice overview in the first post and can still go on discussing in the same Thread.
                          I've seen this in some other forums (nothing to do with flightradar) and it works very well.
                          Cheers

                          Comment


                          • Computer Simulation of 3.5 & 4.5 Element, Open & Shorted Top Coaxial Collinear Antennas

                            Yesterday I have posted results of computer simulations for 4, 6, & 8 element, open top CoCos.
                            I have now done computer simulations for 3.5 & 4.5 Element, Open & Shorted Top CoCos, and results are shown in screenshots below.
                            I have used air insulated model to avoid assumption of Velocity Factor.

                            Reading yesterday's results (post # 824) and this post's results clearly show that:

                            (1) For antennas having even number of full elements, adding an open or shorted half element (1/4 wave element) worsens it's performance.

                            (2) For antennas having odd number of full elements, adding an open half element (1/4 wave element) worsens it's performance, but adding a shorted half element (1/4 wave element) improves it's performance.



                            SCREENSHOT 1 of 4 - Four-and-Half (4.5) Element CoCo - OPEN TOP
                            Gain = 6.74 dBi, SWR = 56.8 (mismatch loss = 11.67 dB)
                            Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 6.74 - 11.67 = -4.93 dBi (i.e. 4.93 dB less than the gain of an isotropic antenna***)
                            coco 4.5 element open at top simulation output.png



                            SCREENSHOT 2 of 4 - Four-and-Half (4.5) Element CoCo - SHORTED TOP
                            Gain = 5.1 dBi, SWR = 6.9 (mismatch loss = 3.54 dB)
                            Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 5.1 - 3.54 = 1.56 dBi
                            coco 4.5 element shorted at top simulation output.png



                            SCREENSHOT 3 of 4 - Three-and-Half (3.5) Element CoCo - OPEN TOP
                            Gain = 7.18 dBi, SWR = 32.5 (mismatch loss = 9.36 dB)
                            Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 7.18 - 9.36 = -2.18 dBi (i.e. 2.18 dB less than the gain of an isotropic antenna.***)
                            coco 3.5 element open at top simulation output.png



                            SCREENSHOT 4 of 4 - Three-and-Half (3.5) Element CoCo - SHORTED TOP
                            Gain = 6.7 dBi, SWR = 6.42 (mismatch loss = 3.3 dB)
                            Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 6.7 - 3.3 = 3.4 dBi
                            coco 3.5 element shorted at top simulation output.png


                            *** An isotropic antenna is a reference hypothetical point antenna, whose gain has been arbirarily assigned a value equal to zero. Antenna gain is measured with reference to it, like elevations are measured with reference to sea level like ".... feet above sea level", and ".... feet below sea level". That is why antenna gain is denoted as "dBi", where "i" means with reference to isotropic antenna.
                            Last edited by abcd567; 2014-04-14, 00:01.

                            Comment


                            • Originally posted by abcd567 View Post
                              Computer Simulation of 3, 4, 6, & 8 Element Coaxial Collinear Antennas

                              I have done computer simulations for above CoCos, and results are shown in screenshots below.
                              I have used air insulated model to avoid assumption of Velocity Factor.

                              SCREENSHOT 1 of 4 - Three (3) Element CoCo
                              Gain = 3.26 dBi, SWR = 14.2 (mismatch loss = 6.1 dB)
                              Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 3.26 - 6.1 = -2.84 dBi
                              [ATTACH=CONFIG]3874[/ATTACH]



                              SCREENSHOT 2 of 4 - Four (4) Element CoCo
                              Gain = 6.87 dBi, SWR = 8.98 (mismatch loss = 4.43 dB)
                              Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 6.87 - 4.43 = 2.44 dBi
                              [ATTACH=CONFIG]3866[/ATTACH]



                              SCREENSHOT 3 of 4 - Six (6) Element CoCo
                              Gain = 8.42 dBi, SWR = 5.86 (mismatch loss = 3.03 dB)
                              Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 8.42 - 5.86 = 2.56 dBi
                              [ATTACH=CONFIG]3867[/ATTACH]



                              SCREENSHOT 4 of 4 - Eight (8) Element CoCo
                              Gain = 9.52 dBi, SWR = 4.63 (mismatch loss = 2.33 dB)
                              Net Gain Seen by Receiver = Antenna Gain - Mismatch Loss = 9.52 - 2.33 = 7.19 dBi
                              [ATTACH=CONFIG]3868[/ATTACH]
                              How are you calculating the initial element gain?
                              When I went to radio school (tongue in cheek there) 4 element 3 db gain, "doubling 3db effect" means 8 elements 6db gain, 16 elements 9 db gain, so curious how you get these values you start with.

                              Cheers

                              Comment


                              • Originally posted by Ressy View Post
                                How are you calculating the initial element gain?
                                When I went to radio school (tongue in cheek there) 4 element 3 db gain, "doubling 3db effect" means 8 elements 6db gain, 16 elements 9 db gain, so curious how you get these values you start with.

                                Cheers
                                I did not put in or assumed any value of Gain or SWR.
                                These are OUTPUT from simulation software.
                                My input was only GEOMETRY of the antenna, the frequency (1090 MHz) and impedance of receiver (50 Ohms), and point of feed (bottom of antenna).

                                The software does not operate by rule of thumb "doubling effect", but actually calculates by splitting antenna into small segments, and enumerating the electromagnetic field produced by these elements using the method "Numeric Electromagnetic Code" (NEC). The software I use is named "4nec2". (Free of charge download from http://www.qsl.net/4nec2/)

                                For more info, please read article in Wikipedia:http://en.wikipedia.org/wiki/Numeric...magnetics_Code.

                                .
                                Last edited by abcd567; 2014-04-14, 00:49.

                                Comment

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