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  • Originally posted by abcd567 View Post

    I did make the one with 53mm long, 5mm dia, 16 turn coil, and did measure SWR. Please see this post:

    https://forum.flightradar24.com/foru...150#post184150

    However I did NOT make the one with your coil. You made it, and based on your measurements, I did computer simulation and posted results of simulation




    This is Flightaware antenna with pvc pipe removed.

    image_10493.jpg
    That is interesting - the top looks very similar to what we've been discussing but with a 4 or 5 turn coil. Could I please ask you to run your computer simulation using your measurements 60,53,137 mm but with 1.5 mm copper wire coil (1.54 mm with insulation) of 6.9 mm diameter (Wire centre to wire centre), 8.44 mm overall. It should be much worse than what you achieved but I'm curious as to how different it is to the 10 turn close wound.

    Scroggie

    Comment


    • Originally posted by Scroggie View Post
      Could I please ask you to run your computer simulation using your measurements 60,53,137 mm but with 1.5 mm copper wire coil (1.54 mm with insulation) of 6.9 mm diameter (Wire centre to wire centre), 8.44 mm overall. It should be much worse than what you achieved but I'm curious as to how different it is to the 10 turn close wound.

      Scroggie
      Will run simulation this weekend.

      Comment


      • Any one interested to run simulation himself/herself, can download modelling software 4nec2 (free of cost) fromhere:

        Download 4NEC2 Software (free of cost)


        Also, I have uploaded my following simulation model files to DropBox. Anyone can download these from Dropbox and run in software 4NEC2.

        Monopole with Coil and Ground Plane.nec

        Super J-Pole with Coil.nec

        .

        Comment


        • Originally posted by abcd567 View Post
          Any one interested to run simulation himself/herself, can download modelling software 4nec2 (free of cost) fromhere:

          Download 4NEC2 Software (free of cost)


          Also, I have uploaded my following simulation model files to DropBox. Anyone can download these from Dropbox and run in software 4NEC2.

          Monopole with Coil and Ground Plane.nec

          Super J-Pole with Coil.nec

          .
          That great - will have a look at that.
          Incidentally I've been experimenting today and cannot replicate the success I had at first with the close wound coil of 10 turns. Throughout today your design has been noticeably better albeit with 1 mm wire.(same dimensions 60,53,137)
          In the last hour I've modified an eBay purchased magnetic -mount identical to the one you show in an earlier post. I too found it to be very poor but it occurred to me that if the top section was 137mm it might be usable. So I exposed the metal at the top and soldered on some 1.5 mm copper to increase that section above the coil to 137 mm. Yesterday I had made six quarter-wave radials at 45 degrees mounted on an F - SMA adapter so it's now a simple matter to experiment with different elements by just plugging them in. So this modified eBay antenna (minus it's magnetic base) is installed waiting for tomorrows signals. I've added a short piece of wire at the bottom to compensate for length that was inside the base that I have removed. As soon as I connected it, even from the bedroom window a couple of aircraft were visible at 200nm. It certainty looks good but with only 8 aircraft over the UK at the moment I'll have to wait until tomorrow to see just how good.

          Scroggie

          Comment


          • Originally posted by Scroggie View Post

            So this modified eBay antenna (minus it's magnetic base) is installed waiting for tomorrows signals. I've added a short piece of wire at the bottom to compensate for length that was inside the base that I have removed. As soon as I connected it, even from the bedroom window a couple of aircraft were visible at 200nm. It certainty looks good but with only 8 aircraft over the UK at the moment I'll have to wait until tomorrow to see just how good.

            Scroggie
            1. Vertical length Inside magnetic base is about 10 to 15 mm depending on make of antenna.

            Optimized whip inside.jpg


            2. If you keep the magnetic base, and place it on a large metallic can, you get a good ground plane, and dont need to add radials. This is exactly what I have done. The Butter Cookies lid is providing a good ground plane, no need of radials.


            Coiled Collinear and Quarter Wave.jpg

            Comment


            • Originally posted by abcd567 View Post

              2. If you keep the magnetic base, and place it on a large metallic can, you get a good ground plane, and dont need to add radials. This is exactly what I have done. The Butter Cookies lid is providing a good ground plane, no need of radials.

              Do you suggest to keep the plastic bottom of these antennas or to remove it before putting it on a metal surface?

              Comment


              • Originally posted by Mephisto View Post

                Do you suggest to keep the plastic bottom of these antennas or to remove it before putting it on a metal surface?
                No need to remove plastic adhesive covering of the base. I have once removed the black plastic adhesive circle from base, but it did not give any improvement. Even with plastic in place, there is enough capacitive coupling between base metal and the food can.
                Last edited by abcd567; 2020-04-21, 19:02.

                Comment


                • Mag Mount Antenna’s Whip Replaced By V-Stub Wire Collinear

                  Comparison of "V-Stub Wire Collinear Whip" with "52mm Optimized Whip"


                  V_stub_wire_collinear_vs_52mm_whip-c.jpg


                  Thin (0.5 mm dia) Steel Tie Wire used to make collinear whip with V-stub.
                  Thin wire can easily be wrapped over threaded stud of magnetic base.

                  Steel Tie Wire.jpg


                  MEASURED PARAMETERS: V-Stub Collinear Whip


                  SWR.jpg


                  R_X_Z_SWR.jpg


                  AIRCRAFTS SEEN & MESSAES RECEIVED (per sec)

                  aircraft-messages.png


                  .
                  Last edited by abcd567; 2020-06-19, 17:16.

                  Comment


                  • My approach to building an antenna with a sma connector and copper wire:

                    sma.pngthreaded.jpg
                    bottem.jpg
                    solder.jpgfranklin_spider.jpg
                    Last edited by buenti; 2020-09-09, 22:58.

                    Comment


                    • I am using this rtl-sdr dongle with Homeassitant. FR24 is installed in docker. Which port is this and which antenna I can use with it? How can I use the following antenna https://www.daraz.pk//products/i2274...L&urlFlag=trueb04d57081307991260a68871841afc95.jpg58e00ad19b6245c536f2d5bb1dbd46d5.jpg

                      Comment


                      • Known as MMCX or mini-sma

                        The antenna looks like it might be normal or RP-SMA (reverse pin)

                        It would need a MMCX-SMA short length. Or some good coax and use a MMCX 'pigtail' between. Just remember each connector adds a little loss.
                        Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                        Comment


                        • Originally posted by Oblivian View Post
                          Known as MMCX or mini-sma

                          The antenna looks like it might be normal or RP-SMA (reverse pin)

                          It would need a MMCX-SMA short length. Or some good coax and use a MMCX 'pigtail' between. Just remember each connector adds a little loss.
                          Should I buy this antenna or DIY a new one myself?
                          this is my theoretical range but I get only 32NM using the antenna which came with the dongle.
                          WhatsApp Image 2021-09-16 at 11.56.11 AM.jpeg

                          Comment


                          • Did you cut the top of the antenna down and put it on a can?

                            I can't make that decision from this side of the world. All those commercial ones are far too expensive in our local value.
                            But a DIY from wire to test may be a cheaper investment to try. Many use home-made and have good range.
                            Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                            Comment


                            • raptor22:

                              Please brows these two threads
                              :


                              3 EASY ANTENNAS FOR BEGINNERS



                              QUICK SPIDER - No Soldering, No Connector



                              .

                              Comment


                              • Originally posted by Oblivian View Post
                                Did you cut the top of the antenna down and put it on a can?

                                I can't make that decision from this side of the world. All those commercial ones are far too expensive in our local value.
                                But a DIY from wire to test may be a cheaper investment to try. Many use home-made and have good range.
                                Do I need a filter?
                                Here is my data capture record
                                Screenshot 2021-09-17 195508.png

                                Comment

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