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  • Originally posted by VE6CPP View Post
    I inquired a while back regarding the Receivers Noise Floor Specs.. which I now see is '2db'..so changing the 'supplied feedline'.. It is H155 cable, 29.6 dB/100m or 9 dB/100ft and 30 feet is 2.7 dB loss.

    If you replace with LMR400 which for 50 feet is about 2.1 dB loss..Surprising as it sounds, you will not see much, if Any, improvement. You would be hard pressed to detect distance change related to a a 0.6 dB change in front end NF of 2db.

    Seems to me your only avenue to greater distance is a higher antenna or an antenna with 2 or 3 dBi more gain.
    Guenter mentions 5 dBi as the gain of the standard FR24 antenna, and you'd need one at least twice as long to see 3 dBi gain improvement.
    Put the supplied antenna as 'High as Possible'..with the supplied co-ax, probably the 'surest way' to increase your distance...or build a 'larger antenna' I guess !
    Jerry
    F-CYQL1
    I'd say add height if possible - get it clear of nearby line of sight obstructions - surprising the good it does.

    Comment


    • Originally posted by peterhr View Post
      How would it work if made from copper brake pie (3/16")? - easy to find on ebay ... it would probably flatten making the bends though.
      I ran a simulation for Squeezed Franklin using 3/16" (4.75 mm) dia tube.

      The Squeezed Franklin does not behave properly when wire dia exceeds 2.5 mm.
      Simulation with 3/16" (4.75 mm) tube, when tweaked to get a good Gain, resulted in very high SWR. which could not be brought down to a reasonable value even with adjustments of matching stub.
      When I tweaked it to get a reasonably good SWR, the Gain became very low.

      A failed experiment!!!

      Why dont you try a normal Franklin which can be installed outdoors?

      See this site to get a guidance for method of construction of outdoor type Franklin:
      http://www.lesaunier.com/htm/franklin1_eng.htm

      I am posting below few pictures from above site for your quick reference:

      franklin_7.JPG...franklin_8.JPGfranklin_3.jpg Franklin_gabarit.jpg
      .
      Last edited by abcd567; 2014-04-27, 23:50.

      Comment


      • Originally posted by peterhr View Post
        I'd say add height if possible - get it clear of nearby line of sight obstructions - surprising the good it does.
        Nearby obstructions in my antenna's line of sight are my main problem.
        I cannot raise antenna to my building's roof-top, as my Building's Management did not allow this , and the owners of surrounding tall buildings have no program to demolish their buildings in near future

        Comment


        • Originally posted by VE6CPP View Post
          Guenter mentions 5 dBi as the gain of the standard FR24 antenna, and you'd need one at least twice as long to see 3 dBi gain improvement.
          ...or build a 'larger antenna' I guess !
          The Guenter antenna is a 3.5 element Collinear. http://ads-b.ca/00-00.htm

          I was planning on making a 14 element Collinear, but after discussing this idea with a radio engineer this is what his thoughts were.

          The issue of having so much gain is the actual beamwidth and elevation of
          the main lobe. More gain = lower elevation and narrower lobe which is great
          for reception at ground level, but how will it fare at aircraft overhead?
          Are we going to experience a wider cone of silence at that point?


          So the antenna will have lots of gain and look downward... great if it's being used as a WiFi antenna, but not for seeing aircraft in the sky.

          So my plan now is to make a slightly longer Guenter antenna of 5.5 elements that should give me about 2.5dB gain more and still have good range too... I hope.

          The only way to know for sure will be to build it and test it up on the tower.
          Last edited by 1090 MHz; 2014-04-28, 05:53.
          www.ADS-B.ca

          Comment


          • Originally posted by peterhr View Post
            How would it work if made from copper brake pie (3/16")? - easy to find on ebay ... it would probably flatten making the bends though.
            Here is a normal 6-element Franklin made from 3/16 inch (4.76 mm) dia copper pipe:
            Gain = 9.13, SWR = 1.18

            Franklin, 6 element, made of 3by16 in (4.76 mm) pipe, with Matching Stub.png
            Last edited by abcd567; 2014-04-28, 03:47.

            Comment


            • Originally posted by 1090 MHz View Post
              The Guenter antenna is a 3.5 element Collinear. http://ads-b.ca/00-00.htm

              I was planning on making a 14 element Collinear, but after discussing this idea with a radio engineer this is what his thoughts were.

              The issue of having so much gain is the actual beamwidth and elevation of
              the main lobe. More gain = lower elevation and narrower lobe which is great
              for reception at ground level, but how will it fare at aircraft overhead?
              Are we going to experience a wider cone of silence at that point?


              So the antenna will have lots of gain and look downward... great if it's being used as a WiFi antenna, but not for seeing aircraft in the sky.

              So my plan now is to make a slightly longer Guenter antenna of 5.5 elements that should give me about 2.5dB gain more and still have good range too... I hope.
              I agree with you. Couple of months ago, on your advise (thanks), I made and put on trial run the 3.5 element CoCo based on Guenter Antenna http://ads-b.ca/00-00.htm, but mine was without Balun. It gave good results. If I have added the Balun, it would improve further.
              Last edited by abcd567; 2014-04-28, 03:42.

              Comment


              • what kind of wire is that? here -> http://ads-b.ca/00-00.htm
                actually i added that quarter wavelength cable to my antenna and wow a nice improvement in all directions i would like to make a perfect copy of that antenna so please tell me the cable i can use to make it
                RTL SDR : T-VEVZ1

                Comment


                • Originally posted by charan View Post
                  what kind of wire is that? here -> http://ads-b.ca/00-00.htm
                  actually i added that quarter wavelength cable to my antenna and wow a nice improvement in all directions i would like to make a perfect copy of that antenna so please tell me the cable i can use to make it
                  RG402 semi-rigid co-ax,
                  Velocity factor 69.5, 1/2-wave =95.58mm, 1/4-wave = 47.79mm.
                  The above lengths are for free-field antennae, thay will need adjusting to allow for plastic housing but by how much I cannot say.
                  I have some on order from china via ebay to do the same.
                  Ben.
                  FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                  Comment


                  • Originally posted by F-EGLF1 View Post
                    RG402 semi-rigid co-ax,
                    Velocity factor 69.5, 1/2-wave =95.58mm, 1/4-wave = 47.79mm.
                    The above lengths are for free-field antennae, thay will need adjusting to allow for plastic housing but by how much I cannot say.
                    I have some on order from china via ebay to do the same.
                    Ben.
                    Ahh thanks will order
                    RTL SDR : T-VEVZ1

                    Comment


                    • Originally posted by charan View Post
                      what kind of wire is that? here -> http://ads-b.ca/00-00.htm
                      actually i added that quarter wavelength cable to my antenna and wow a nice improvement in all directions i would like to make a perfect copy of that antenna so please tell me the cable i can use to make it
                      The top quarter wavelength element is for reducing SWR (i.e impedance matching). That is why your antenna's performance improved by adding it.

                      If you look closely, you will notice that at the top of 1/4 wavelength piece, the core is shorted (soldered) to braid.
                      Was you quarter wavelength piece open or shorted at top?

                      Couple of months ago, on advise from forum member "1090MHz" (who gave me the link http://ads-b.ca/00-00.htm, many thanks to him), I built my 3.5 element CoCo using RG6 cable assuming 0.8 velocity factor. It gave good results.

                      Since my cable was from an unknown manufacturer, whose cable data sheet was not available, for my first CoCo I ASSUMED VF =0.8. Later from same reel of cable, I made several more 3.5 CoCos using VF 0.77, 0.83, 0.86, and found the one with VF 0.83 worked best.

                      The VF 0.83 may not be applicable to all RG6 cables, as VF of cable from different manufacturer varies from manufacturer to manufacturer. This is because the insulation used in RG6 is Foamed PolyEthylene, and VF depends on amount of Foaming used by each manufacturer. In my opinion the best way is to use cable from a manufacturer whose data sheets are available, so that VF can be known with surety, and there are no assumptions and consequent risk of reduction in performance.

                      I have tried 4 CoCos, made of RG6, with following element lengths
                      VF = 0.77, 1/2 wavelength element = 10.6 cm
                      VF = 0.80, 1/2 wavelength element = 11.0 cm
                      VF = 0.83, 1/2 wavelength element = 11.4 cm
                      VF = 0.86, 1/2 wavelength element = 11.8 cm

                      .
                      Last edited by abcd567; 2014-04-28, 15:05.

                      Comment


                      • @F-EGLF1:
                        I noted "F-EGLF1, Blitzortung station 878" at bottom of your message.
                        I googled "Blitzortung" and reached their site http://www.blitzortung.org/Webpages/index.php?lang=en. Interesting site for live data for Lightning (Blitz in German). It seems you have the equipment installed & contributing data as "Blitzortung station 878". Great!!!

                        Comment


                        • Originally posted by abcd567 View Post
                          @F-EGLF1:
                          I noted "F-EGLF1, Blitzortung station 878" at bottom of your message.
                          I googled "Blitzortung" and reached their site http://www.blitzortung.org/Webpages/index.php?lang=en. Interesting site for live data for Lightning (Blitz in German). It seems you have the equipment installed & contributing data as "Blitzortung station 878". Great!!!
                          Yes, a facinating hobby, homebrew antennas and a kit comprising 2 pcb's and components (some surface mount) that you have to build and program yourself, You may also notice station 843 posting here (T-EGLF8) (particularly in this section) we compete on a friendly basis and share ideas for both Blitzortung and FR24.
                          Ben.
                          (Another user F-EGPN1 is also a Blitzortung feeder far to the north of me)
                          Last edited by F-EGLF1; 2014-04-28, 16:56.
                          FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

                          Comment


                          • Originally posted by abcd567 View Post
                            The top quarter wavelength element is for reducing SWR (i.e impedance matching). That is why your antenna's performance improved by adding it.

                            If you look closely, you will notice that at the top of 1/4 wavelength piece, the core is shorted (soldered) to braid.
                            Was you quarter wavelength piece open or shorted at top?

                            Couple of months ago, on advise from forum member "1090MHz" (who gave me the link http://ads-b.ca/00-00.htm, many thanks to him), I built my 3.5 element CoCo using RG6 cable assuming 0.8 velocity factor. It gave good results.

                            Since my cable was from an unknown manufacturer, whose cable data sheet was not available, for my first CoCo I ASSUMED VF =0.8. Later from same reel of cable, I made several more 3.5 CoCos using VF 0.77, 0.83, 0.86, and found the one with VF 0.83 worked best.

                            The VF 0.83 may not be applicable to all RG6 cables, as VF of cable from different manufacturer varies from manufacturer to manufacturer. This is because the insulation used in RG6 is Foamed PolyEthylene, and VF depends on amount of Foaming used by each manufacturer. In my opinion the best way is to use cable from a manufacturer whose data sheets are available, so that VF can be known with surety, and there are no assumptions and consequent risk of reduction in performance.

                            I have tried 4 CoCos, made of RG6, with following element lengths
                            VF = 0.77, 1/2 wavelength element = 10.6 cm
                            VF = 0.80, 1/2 wavelength element = 11.0 cm
                            VF = 0.83, 1/2 wavelength element = 11.4 cm
                            VF = 0.86, 1/2 wavelength element = 11.8 cm

                            .
                            Yes it was shorted at the top
                            and i'm thinking to order RG402 cable. will there be any improvement with coco antenna or is the same? and also i don't know the VF of my current coaxial and i jus used 11cm.. and i dont have the cable now to make it so i have to buy it. so which would be the better ? RG402 or RG6?
                            RTL SDR : T-VEVZ1

                            Comment


                            • results from my 7 and a half well its a 8 trimmed down to tune it, so its almost a 7.5 element (its open ended at the moment) i will go and make it a 7.5 with a proper shorted top to see how it fairs.
                              for reference first the 3 and a half
                              3_5_Shorted.jpg

                              7.5.jpg
                              7_and abit_held .jpg

                              i also trimmed up the j-pole to see if it would maje any difference.
                              j_pole_trimmed.jpg
                              Last edited by SpaxmoidJAm; 2014-04-28, 19:15.
                              T-EGLF8

                              Comment


                              • Originally posted by charan View Post
                                what kind of wire is that? here -> http://ads-b.ca/00-00.htm
                                actually i added that quarter wavelength cable to my antenna and wow a nice improvement in all directions i would like to make a perfect copy of that antenna so please tell me the cable i can use to make it
                                I believe it's RG174. Also the outer shield is dipped in solder to make it ridged solid.

                                *UPDATE*

                                The coax used is now confirmed to be RG402

                                $T2eC16V,!ygE9s7HI7osBRLrzTFUBw~~60_12.JPG
                                Last edited by 1090 MHz; 2014-04-28, 23:16.
                                www.ADS-B.ca

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