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  • Originally posted by T-KJAN4 View Post
    Gonna build one of these today, I have plenty of RG213.
    http://f5ann.pagesperso-orange.fr/An..._MHz_FR_EN.jpg
    After you build and use this antenna, please post maximum coverage obtained by it.

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    • Will do, just waiting on the female N socket to arrive......... I have all the other materials

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      • Originally posted by T-KJAN4 View Post
        Will do, just waiting on the female N socket to arrive......... I have all the other materials
        I don't want to discourage you, but just a caution note: Coco is a tricky thing. Many persons got very good results, but also a large number, including me, got frustratingly poor results. I wish your coco performs good, but if it does not, don't get frustrated.
        Last edited by abcd567; 2014-09-15, 20:37.

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        • Thanks all for input as usual. After some more research and a bit of a discussion with my dad I have decided to clean and solder wipe each element. Should stop any corosion without messing with signal. After showing him this thread i got him interested and he is keen on trying a coco he scored some plans for. Cos he's old and got the shakes i will do the fine work but its his idea to try something different as a comparison against the groundplane. Due to original design this will be a straight uncouple and recouple. Will post findings as they come to light. Thanks again

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          • I have a Clear Polyurethane UV stable waterborn glaze i think would be better than varnish/laquers due to its longevity but based on initial reading of coatings distorting signals i have stayed "clear" (no pun intended) till now.
            Whip.jpg

            I built this collinear whip from copper wire and coated it with clear varnish - afterwards it would not work any more, so dont coat with varnish it has the same near effect as pvc pipe

            Mike

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            • Originally posted by abcd567 View Post
              Thanks Mike for the practical tip.

              Did you download & run the .nec file (for your fiber glass double coil whip) which I have attached with my post few days ago? In that post I forgot to tell following step:

              After hitting calculate button (or F7), a popup will open. It will have "Use Existing File" selected by default. Choose "Far Field Pattern" & hit "generate" button.
              abcd567, I downloaded your n4nec file of my whip, and have been experimenting with changing things around and see the results, its very helpful. I am trying to add more of the same coil / elements to the top, but cant figure it out . Maybe you can explain how to do this or maybe just add some elements to it and I can download again, so I can see how its done.
              Thanks
              Mike

              Comment


              • Originally posted by Stephen P View Post
                Thanks all for input as usual. After some more research and a bit of a discussion with my dad I have decided to clean and solder wipe each element. Should stop any corosion without messing with signal. After showing him this thread i got him interested and he is keen on trying a coco he scored some plans for. Cos he's old and got the shakes i will do the fine work but its his idea to try something different as a comparison against the groundplane. Due to original design this will be a straight uncouple and recouple. Will post findings as they come to light. Thanks again
                (1) Solder wipe is actually small scale tinning, an alternative to factory tinned copper wire. It is a very practical solution if wire length is not large, which is your case.

                (2) Waiting to see results of your CoCo project.

                (3) A close look of your spider antenna photo showed that the ground plane wires are much longer than the quarter-wave vertical whip. Most of designs of spider antenna I have seen recommend ground plane wires to be quarter-wave length.

                I have taken measurement of your spider antenna photograph, reference being the vertical whip which I took 69mm long, and used to scale other dimensions. I found your ground plane wires are 90mm long, the metallic Flange to which the ground plane wires are soldered is 36mm dia, and the ground plane wires are bent down 45 degrees.

                I then modeled and ran computer simulation with 90mm long ground plane wires.
                The results were Gain = 6.45 dBi, SWR = 8.

                Since the SWR was very high, I ran the simulation again, this time using ground plane wire length of 69mm (quarter-wave length).
                The results were Gain = 5.7 dBi, SWR = 1.94.

                I am attaching below the screenshots of two simulations for your reference.

                Spider 90mm legs.PNG ... Spider 69mm legs.PNG ... Stephens Spider 3.jpg
                Last edited by abcd567; 2014-09-16, 15:19.

                Comment


                • Originally posted by YWYY View Post
                  abcd567, I downloaded your n4nec file of my whip, and have been experimenting with changing things around and see the results, its very helpful. I am trying to add more of the same coil / elements to the top, but cant figure it out . Maybe you can explain how to do this or maybe just add some elements to it and I can download again, so I can see how its done.
                  Thanks
                  Mike
                  OK, I will add more elements, and upload the new .nec file, but I may not be able to do this for next couple of days due to some urgent personal business.

                  Comment


                  • Originally posted by YWYY View Post
                    abcd567, I downloaded your n4nec file of my whip, and have been experimenting with changing things around and see the results, its very helpful. I am trying to add more of the same coil / elements to the top, but cant figure it out . Maybe you can explain how to do this or maybe just add some elements to it and I can download again, so I can see how its done.
                    Thanks
                    Mike
                    Hi Mike,
                    I'm glad it's not just me who is struggling with 4NEC2. I found a series of videos on YouTube by dx2hunt which I found helpful. This is the first. My problem seems to be that I only think in 2 dimensions. I can't cope with 3 !! There is a forum but most of the questions are far too advanced for me.
                    Cheers
                    Dave
                    T-EGUB1

                    Comment


                    • Has anyone used this antenna with their setup, or did any test with it ?
                      The last antenna on the page.

                      Chinese 9db Antenna
                      http://www.nicstorey.co.uk/planeplot...ntenna%20Range
                      Brian

                      www.RadarSpotters.eu
                      [ Feeder Station List ][ Map ][ Latest Feeders Rank Stats ][ ImRadarFeeder.com Radar Feeders WorldWide Map ][ VRS Feeder List ] (NEW)

                      Comment


                      • Originally posted by SoCalBrian View Post
                        Has anyone used this antenna with their setup, or did any test with it ?
                        The last antenna on the page.

                        Chinese 9db Antenna
                        http://www.nicstorey.co.uk/planeplot...ntenna%20Range
                        I have one, however it is still in my bedroom as I have not got up on the roof yet, but it looks good, the build quality is fantastic, and it is picking up quite a few aircraft.
                        I think it will be very good when it is on the roof.
                        ben.
                        FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                        Comment


                        • Originally posted by F-EGLF1 View Post
                          I have one, however it is still in my bedroom as I have not got up on the roof yet, but it looks good, the build quality is fantastic, and it is picking up quite a few aircraft.
                          I think it will be very good when it is on the roof.
                          ben.
                          Trying to locate where to get this antenna from but no joy yet. Where did you order it from?

                          Comment


                          • Originally posted by North Borneo Radar View Post
                            Trying to locate where to get this antenna from but no joy yet. Where did you order it from?
                            You will have to ask Nic about that, I bought it through him.
                            Ben.
                            FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                            Comment


                            • Originally posted by North Borneo Radar View Post
                              Trying to locate where to get this antenna from but no joy yet. Where did you order it from?
                              It may be here.
                              http://ikhiwa.com/shop/index.php?id_...roller=product

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