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  • I cut my cable to the exact length... and do my own connector installations... it's not that hard with the right tools.

    www.ADS-B.ca

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    • I have downloaded an antenna modelling and optimization software "4NEC2" from:
      http://www.qsl.net/4nec2/ .
      It is not as sophisticated as the commercial software EZNEC, but it is very good considering that it is free of cost.

      I then simulated Franklin I have built, and following 3 screenshots show the results:
      (see screenshot 3 - maximum gain =6.95 dBi, SWR =2.49 when connected to 75 ohms cable/receiver)

      1 - INPUT - WIRE GEOMETRY DATA
      4nec2-franklin-input-geometry data.png

      2 - INPUT - LOAD/SOURCE DATA
      4nec2-franklin-input-source-load-data.png

      3 - OUTPUT - SWR, GAIN, IMPEDANCE, RADIATION PATTERN
      4nec2-franklin-output-gain-swr-pattern.jpg

      4 - OUTPUT - SWR vs FREQUENCY SWEEP
      4nec2-franklin-output-sweep.png

      Edited: Originally posted screenshots have been replaced on 28 January 2014, after correction of error in source/load configuration, and re-runnig the modeller's calculator.
      .
      Last edited by abcd567; 2014-01-29, 07:53.

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      • Franklin Antenna Gain = 7.15 dBi, SWR = 1.1

        I have done some changes in impedance matching arrangement and then simulated the new design with 4nec2 software.

        STRATEGY:
        (1) Determine Antenna Impedance. This is done by Simulation of antenna without matching stub. (I have assumed 1600 ohms in the previous design, which was wrong approach, and proved to be too high).
        (2) Using the antenna impedance Zant & connecting cable impedance Zcab, determine required matching stub impedance Zstb , using formula Zstb = √(Zant x Zcab).
        (3) Using stub impedance obtained in (3) above, and the stub wire dia d, calculate center-to-center spacing between stub conductors S, using formulae Zstb = 276 log (2S/d).
        (4) Simulate antenna WITH matching stub using dimensions obtained as in (3) above.

        CALCULATIONS:

        To get fairly accurate value of antenna impedance, I ran the simulation after removing the impedance matching stub and connecting feeder cable directly to antenna at its center.
        The results show that the Antenna Impedance = 411 - j435 ohms

        Using the Antenna Impedance obtained above (411 - j435 ohms)
        Zant= √(4112 + 4352 ) = 598 ohms. The previous design's assumed value of 1600 ohms was therefore wrong.

        Based on new value of Antenna impedance obtained by simulation, I did following calculation for the dimensions of matching stub which worked out to be 3mm stub conductor spacing for a wire dia of 1mm. See calculations below.


        Required impedance of Matching Stub Zstb = √(Zant x Zcab) = √(598 x 75) = 212 ohms

        Stub Dimension calculation:
        S= spacing between stub conductors (center-to-center)
        d= dia of stub wire = 1mm (#18AWG)

        Zstb = 276 log (2S/d)

        which can be rearranged as S = (d/2) x 10 (Zstb/276)
        Using d = 1mm and Zstb = 212 ohms,
        S = (1/2) x 10 (212/276) = 3mm

        I then simulated with a 3mm stub (wire #6, #7 & #8 in input gemetry, first scteenshot below). The wire #14 is the point of connection of coaxial cable to the stub.

        Please see input & output data in the 4 screenshots below (Gain = 7.15 dBi, SWR = 1.1 - see image 3, left window):


        Image 1 of 4 - input data - geometry
        3mm stub-franklin-input-geometry data.png

        Image 2 of 4 - input data - source/load
        3mm stub-franklin-input-source-load-data.png

        Image 3 of 4 - output data - gain, swr impedance, pattern
        3mm stub-franklin-output-gain-swr-pattern.png

        Image 4 of 4 - output data - frequency sweep vs swr
        3mm stub-franklin-output-sweep.png


        .
        Last edited by abcd567; 2014-02-01, 00:59.

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        • Effect of Wire Dia on Gain & SWR - Franklin Collinear

          I have run another simulation on 4nec2 software http://www.qsl.net/4nec2 for Franklin collinear, this time varying wire dia from 1 mm to 2 mm in 4 steps, and keeping all dimensions same.

          The result shows that Franklin with 2 mm dia wire has a higher gain & lower SWR than the Franklin with 1mm dia wire.
          Please see screenshot of Wire Dia vs SWR & Gain below:

          Table of SWR & Gain vs Wire Dia:
          franklin wire size.PNG


          Dimensions Diagram for Franklin
          franklin-1mm to 2mm wire-4mm fold-5mm stub-how-to.jpg






          .
          Last edited by abcd567; 2014-02-10, 03:16.

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          • Franklin - Effect of matching stub's wire spacing on Gain & SWR.
            Please see screenshot of 4nec2 software simulation below:
            uploadfromtaptalk1392155815189.jpg


            .
            Last edited by abcd567; 2014-02-12, 00:36.

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            • I found this on my doorstep today to my surprise!

              fa-1.jpgfa-3.jpgfa-2.jpg
              www.ADS-B.ca

              Comment


              • Originally posted by 1090 MHz View Post
                I found this on my doorstep today to my surprise!

                [ATTACH=CONFIG]3340[/ATTACH][ATTACH=CONFIG]3341[/ATTACH][ATTACH=CONFIG]3342[/ATTACH]
                What's included? (looks like a good length of down lead)

                Comment


                • Originally posted by 1090 MHz View Post
                  I found this on my doorstep today to my surprise!

                  [ATTACH=CONFIG]3340[/ATTACH][ATTACH=CONFIG]3341[/ATTACH][ATTACH=CONFIG]3342[/ATTACH]
                  Originally posted by peterhr View Post
                  What's included? (looks like a good length of down lead)

                  From FlightAware Page:

                  FlightFeeder Kit Contents
                  FlightFeeder
                  External Antenna (1' / 300mm antenna, total size 2' / 600mm with mounting bracket and antenna cable)
                  Antenna cable, low-loss with SMA connectors (length choice of 1m, 3m, 5m, or 15m)
                  Ethernet (length choice of 1m, 3m, 5m, or 10m)
                  USB power cable (with local plug or adapter)

                  Obtaining a FlightFeeder
                  In January 2014, FlightAware began shipping FlightFeeders for free to sites that currently have limited to no FlightAware ADS-B coverage.
                  In February 2014, FlightAware will begin selling FlightFeeder for immediate delivery.

                  Comment


                  • Wish someone would sponsor me a box!

                    Comment


                    • Originally posted by HermanZA View Post
                      Wish someone would sponsor me a box!
                      You can get the box!
                      Step1: Register http://flightaware.com/account/join/,
                      Step2: Request hardware/software http://flightaware.com/adsb/request.

                      Also see this page for details http://flightaware.com/adsb/flightfeeder/.

                      .

                      Comment


                      • Originally posted by HermanZA View Post
                        Wish someone would sponsor me a box!
                        If you're in Kimberley, South Africa I'm sure you'll get one if you ask. They currently have a big push on now to build their own ADS-B and MLAT network.

                        The Flight Aware box, which I've looked inside, contains a very nice and expensive dual channel Mode-S Beast Mark II radio card:
                        http://www.modesbeast.com/scope.html
                        It's connected to a Raspberry Pi by USB internal connection.

                        The bank of LED's on the beast card are sadly tucked inside the FA case and are not visible from the outside. I drilled 7 holes and set the LED's through the side panel... as seen here:

                        This is what the LED each represent ... which is always coo, to monitor.
                        http://www.myway.de/mode-s-beast/Eng...Jumpers_o.html

                        Beast-LEDs.jpg
                        Last edited by 1090 MHz; 2014-02-16, 03:31.
                        www.ADS-B.ca

                        Comment


                        • Originally posted by 1090 MHz View Post
                          If you're in Kimberley, South Africa I'm sure you'll get one if you ask. They currently have a big push on now to build their own ADS-B and MLAT network.

                          The Flight Aware box, which I've looked inside, contains a very nice and expensive dual channel Mode-S Beast Mark II radio card:
                          http://www.modesbeast.com/scope.html
                          It's connected to a Raspberry Pi by USB internal connection.

                          The bank of LED's on the beast card are sadly tucked inside the FA case and are not visible from the outside. I drilled 7 holes and set the LED's through the side panel... as seen here:

                          This is what the LED each represent ... which is always coo, to monitor.
                          http://www.myway.de/mode-s-beast/Eng...Jumpers_o.html

                          [ATTACH=CONFIG]3343[/ATTACH]
                          Hello 1090Mhz,

                          From the picture and the LED arrangement it appears to be a 1 channel mode s beast. I wonder what they have programmed the Rpi into to get it work ingwith the mode s beast but it is definitely interesting. Any chance of a picture showing the inside? You don't need to if you don't want to. As an owner of a 2CH mode s beast I can definitely say it's a good piece of kit and I hope mine just keeps going for a long time.

                          On another note, are you going to use a cable splitter so that you can use 1 antenna (from FR24) and connect to the FR24 receiver and FA receiver at the same time?

                          Note: I think we need a different thread for this as this is not related to antenna at all!

                          Comment


                          • Originally posted by North Borneo Radar View Post
                            Hello 1090Mhz,

                            From the picture and the LED arrangement it appears to be a 1 channel mode s beast. I wonder what they have programmed the Rpi into to get it work ingwith the mode s beast but it is definitely interesting. Any chance of a picture showing the inside? You don't need to if you don't want to. As an owner of a 2CH mode s beast I can definitely say it's a good piece of kit and I hope mine just keeps going for a long time.

                            On another note, are you going to use a cable splitter so that you can use 1 antenna (from FR24) and connect to the FR24 receiver and FA receiver at the same time?

                            Note: I think we need a different thread for this as this is not related to antenna at all!
                            Splitting the signal would cut the signal in half to each radio .... not something I would want to do, and since I have antennas provided for each radio I will be installing the FA with it's own antenna too.

                            North Borneo email me at radar@ads-b.ca
                            www.ADS-B.ca

                            Comment


                            • Originally posted by abcd567 View Post
                              You can get the box!
                              .
                              Although I have about 310 flights per day in my reception area, It's not deemed "busy enough" by any of the networks to invest in hardware for this part of Africa. And with the local currency so pathetic against the US$ / Euro, purchasing is a *very* expensive option. Take listed price times 11 for $ and about times 16 for Euro.

                              Comment


                              • Originally posted by HermanZA View Post
                                Although I have about 310 flights per day in my reception area, It's not deemed "busy enough" by any of the networks to invest in hardware for this part of Africa. And with the local currency so pathetic against the US$ / Euro, purchasing is a *very* expensive option. Take listed price times 11 for $ and about times 16 for Euro.
                                You won't know until you apply and see if they'll accept you or turn you down.

                                Wouldn't it be nice if they had two kit ranges they could issue - the $500 box for the busy areas and the $150-$200 box to try in the less well trafficked or awkward (valleys in mountain ranges) areas or to provide ground cover at an airport.

                                Comment

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