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  • As I stated, only those who feed via Linux (T feeder) or FR24 FlightFeeder (F feeder). Those using Windows FR24 uploader don't have the stats page. Can't comment if PlanePlotter feeders to FR24 have it or not.
    F-YSWG1 and T-YSWG2

    Comment


    • .
      Note: Tapatalk does not display Tables properly, Browsers do.
      .


      QUICK REFERENCE TABLES


      FORMULAS:
      Item Formula Example
      Antenna 50 Ohm, Receiver 75 Ohm
      Reflection Coefficient Γ Γ = (Z1 - Z2) / (Z1 + Z2) Γ = (75 - 50) / (75 + 50) = 0.2
      Standing Wave Ratio SWR SWR = {(1+Γ) / (1-Γ)} : 1 SWR = {(1+0.2) / (1-0.2)} : 1 = 1.5 : 1
      Mismatch Loss ML dB ML = -10 log (1 - Γ2) ML = -10 log (1 - 0.22) = 0.177 dB

      CALCULATED VALUES:
      Reflection Coefficient 0.00 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00
      SWR 1.00 1.22 1.35 1.50 1.67 1.86 2.08 2.33 2.64 3.00 3.44 4.00 4.71 5.67 7.00 9.00 12.33 19.00 39.00
      Mismatch Loss dB 0.00
      dB
      0.04
      dB
      0.10
      dB
      0.18
      dB
      0.28
      dB
      0.41
      dB
      0.57
      dB
      0.76
      dB
      0.98
      dB
      1.25
      dB
      1.56
      dB
      1.94
      dB
      2.38
      dB
      2.92
      dB
      3.59
      dB
      4.44
      dB
      5.57
      dB
      7.21
      dB
      10.11
      dB

      dB

      .
      Last edited by abcd567; 2014-04-09, 13:57.

      Comment


      • ANOTHER EXPERIMENTAL DESIGN - 6 ELEMENT COILED DIPOLE.
        FITS INSIDE 25mm PVC PIPE


        NOT BUILT & TESTED YET

        Gain = 8.5 dB in horizontal direction, SWR = 1.65

        SEE BELOW SCREENSHOTS OF COMPUTER SIMULATION USING 4NEC2 SOFTWARE
        (available free of cost at http://www.qsl.net/4nec2/)
        :


        SIMULATION OUTPUT: ANTENNA LAYOUT, SWR, GAIN, & PATTERN
        6 section-coiled-dipole-output.jpg

        INPUT: DIMENSIONAL DATA OF ANTENNA, FREQUENCY, CABLE IMPEDANCE, CABLE CONNECTION POINT
        6 section-coiled-dipole-input.jpg

        .
        Last edited by abcd567; 2014-04-01, 14:41.

        Comment


        • Hi ab cd,
          That one looks interesting. I have a bit of wire left so I'll have a go at building it and I'll report back.

          I've tried the coiled whip you posted above but had not much success with or without the ground plane. The Franklin is much better.

          Do you know how well theory translates into practise or do you have to build something to try it out?
          T-EGUB1

          Comment


          • Originally posted by trigger View Post
            Hi ab cd,
            That one looks interesting. I have a bit of wire left so I'll have a go at building it and I'll report back.

            I've tried the coiled whip you posted above but had not much success with or without the ground plane. The Franklin is much better.

            Do you know how well theory translates into practise or do you have to build something to try it out?
            Theory gives fairly accurate results. When the antenna is built, it is never exactly as in theory (i.e. wires not perfect straight lines, wires not perfectly vertical/horizontal, coil not a perfect circle or perfect helix, wire dia & lengths not very accurate etc), so the results may be substantially different. Best is to build-try-trim/adjust-try.

            Sent from my N762 using Tapatalk 2
            Last edited by abcd567; 2014-04-01, 20:12.

            Comment


            • ANOTHER EXPERIMENTAL DESIGN - 5/8 WAVELENGTH DIPOLE WITH TUNING/IMPEDANCE MATCHING COIL.
              FITS INSIDE 25mm PVC PIPE

              NOT BUILT & TESTED YET

              REVISED ON APRIL 03, 2014 DUE TO ERROR IN EARLIER INPUT/OUTPUT DATA

              Gain = 5.81 dBi, SWR = 1.37

              SEE BELOW SCREENSHOTS OF COMPUTER SIMULATION USING 4NEC2 SOFTWARE
              (available free of cost at http://www.qsl.net/4nec2/):


              SIMULATION OUTPUT: ANTENNA LAYOUT, SWR, GAIN, & PATTERN
              dipole+coil-output-R1.png

              INPUT: DIMENSIONAL DATA OF ANTENNA, FREQUENCY, CABLE IMPEDANCE, CABLE CONNECTION POINT
              dipole+coil-input-R1.jpg

              COIL & FEED DETAILS
              dipole-coil-details-R1.png
              Last edited by abcd567; 2014-04-03, 16:35.

              Comment


              • i managed to have a quick play at lunchtime with sprectrum analyser today, i thibk after getting my coupler the right way round i got some readings, the quick and dirty bent bit of wire wedged in a tnc connector did have a resonance near 1090MHz 3 db's or so but the good resonance was down at 860MHz 12 db's.

                Tried to use the network analyser but was got confused by its calibration procedure and ran out of time, once i'm happy and i sort of know what i'm doing i'll get some screen grabs of stuff.
                T-EGLF8

                Comment


                • Originally posted by SpaxmoidJAm View Post
                  i managed to have a quick play at lunchtime with sprectrum analyser today, i thibk after getting my coupler the right way round i got some readings, the quick and dirty bent bit of wire wedged in a tnc connector did have a resonance near 1090MHz 3 db's or so but the good resonance was down at 860MHz 12 db's.

                  Tried to use the network analyser but was got confused by its calibration procedure and ran out of time, once i'm happy and i sort of know what i'm doing i'll get some screen grabs of stuff.
                  Good! Keep it up. We all will benefit from your work

                  Sent from my N762 using Tapatalk 2

                  Comment


                  • please post how to make a resonator coil; turns, diameter etc
                    RTL SDR : T-VEVZ1

                    Comment


                    • Originally posted by charan View Post
                      please post how to make a resonator coil; turns, diameter etc
                      Did you not click the images? they are there.

                      Length required to make turns can be made with antenna 5/8 calculators. Which at 1090mhz is 160mm

                      If they are 1/4 wave coils. The standard length is 56mm
                      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                      Comment


                      • I worked out where i was going wrong with the network analyzer and made a quick aerial this lunchtime, in fact i made the top half of this aerial with four 138mm radial arms for the ground plane


                        6 section-coiled-dipole-output.jpg
                        This was the output
                        test2.jpg

                        although the notch at 1090MHz isnt as big as the one around 860 its got reasonable bandwidth.
                        Last edited by SpaxmoidJAm; 2014-04-04, 15:13.
                        T-EGLF8

                        Comment


                        • Originally posted by SpaxmoidJAm View Post
                          I worked out where i was going wrong with the network analyzer and made a quick aerial this lunchtime, in fact i made the top half of this aerial with four 138mm radial arms for the ground plane


                          [ATTACH=CONFIG]3760[/ATTACH]
                          This was the output
                          [ATTACH=CONFIG]3806[/ATTACH]

                          although the notch at 1090MHz isnt as big as the one around 860 its got reasonable bandwidth.
                          Try to trim the limb lengths slightly. This may improve 1090 MHz notch.

                          Comment


                          • Originally posted by SpaxmoidJAm View Post
                            I worked out where i was going wrong with the network analyzer and made a quick aerial this lunchtime, in fact i made the top half of this aerial with four 138mm radial arms for the ground plane


                            [ATTACH=CONFIG]3760[/ATTACH]
                            This was the output
                            [ATTACH=CONFIG]3806[/ATTACH]

                            although the notch at 1090MHz isnt as big as the one around 860 its got reasonable bandwidth.
                            Try also (1) bend downwards the earth plane wires, so that their tips are say about 40 to 50 mm below horizontal (2) use a little longer earth plae wires say 150 mm instead of 138mm

                            Sent from my N762 using Tapatalk 2

                            Comment


                            • VELOCITY FACTOR OF COAXIAL CABLES:

                              The velocity factor VF of a medium is ratio of velocities of propagation of Electromagnetic waves in that medium (v) and in vacuum (c).

                              The velocity of propagation of Electromagnetic waves in a medium depends on:
                              (1) Medium's electrical characteristic relative permittivity er.png (dielectric constant)
                              (2) Medium's magnetic characteristic relative permeability ur.png (which is the measure of the ability of a material to support the formation of a magnetic field within itself).

                              VF4a.png

                              Velocity Factor
                              VF4b.png

                              Values of Relative permeability ur.png
                              Relative permeability is usually 1 for non-magnetic materials such as cable insulation materials.

                              Values of Relative permittivity er.png
                              • Vacuum = 1 (by definition)
                              • Air = 1.00058986
                              • PTFE/Teflon = 2.1
                              • Polyethylene = 2.25
                              • Foamed Polyethylene = 1.75 to 1.35
                                (foamed polyethylene is a mixture of gas and polyethylene and it's electrical parameters depend on solid to gas proportion)

                              Hence Velocity Factors (VF) are calculated as follows:
                              • For PTFE/Teflon insulated coax, VF = 1 / √(2.1 x 1) = 0.69
                              • For Polyethylene insulated coax, VF = 1 / √(2.25 x 1) = 0.66
                              • For foamed polyethylene insulated coax, the VF ranges between VF = 1 / √(1.75 x 1) = 0.76 & VF = 1 / √(1.35 x 1) = 0.85



                              **Information below is quoted from Coaxial Cable Manufacturer Belden's Catalouge:
                              DIELECTRIC CONSTANT
                              • Symbol: er.png
                              • Very important for electronic cables
                              • Lower er.png = Lower capacitance, Higher impedance, Lower attenuation.
                              • Air is best dielectric (er.png = 1)
                              • Adding air to (foaming) any material lowers its dielectric constant er.png.


                              .
                              Last edited by abcd567; 2014-04-06, 23:04.

                              Comment


                              • Originally posted by abcd567 View Post
                                Try also (1) bend downwards the earth plane wires, so that their tips are say about 40 to 50 mm below horizontal (2) use a little longer earth plae wires say 150 mm instead of 138mm

                                Sent from my N762 using Tapatalk 2
                                That has improved the notch, but I think the inherent problem with this design is that you cannot adjust the other two lengths of the antenna. Making it not the best design to go for if your making your first antenna. That being said 5.5 to 6 db's isn't to bad.

                                test3.jpg

                                what I might try is coupling each stage with a connector so it can be adjusted but again anyone without equipment would be working blind.

                                Think a collinear is next to try.

                                here's the aerial
                                WP_20140404_001.jpg
                                Last edited by SpaxmoidJAm; 2014-04-07, 07:05.
                                T-EGLF8

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