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  • #76
    Looks interesting, what is the antenna actually made of?

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    • #77
      Originally posted by peterhr View Post
      Looks interesting, what is the antenna actually made of?
      It is made of central conductor of the coaxial cable WITH its insulation (white).
      The outer plastic cover and the shield (aluminum foil+braid) of the coaxial were removed to get central conductor with it's insulation.
      The inner copper conductor of coaxial is not thick enough to maintain it's shape.The white insulation adds to the strength of the copper wire to keep it in shape.
      The central conductor's white insulation gives an impression that the antenna is made of white plastic rod :-)

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      • #78
        Understanding this right - so the outer/shield is NOT used for the elements?
        Have you experimented a bit and can perhaps comment on reception difference, in what you are showing here (4 elements) vs say 8 elements?

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        • #79
          Hmm, wonder if you could make one from adhesive foil tape ( like this http://www.ebay.co.uk/itm/MULTI-PURP...-/360430320375 ) stuck to the window

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          • #80
            Originally posted by HermanZA View Post
            Understanding this right - so the outer/shield is NOT used for the elements?
            Have you experimented a bit and can perhaps comment on reception difference, in what you are showing here (4 elements) vs say 8 elements?
            You understood this right - the outer/shield is NOT used for the elements, only inner core with its insulation.
            The insulation is used to give mechanical strength to the inner core, so that it stands erect and maintains it's shape.

            I have not tried 8 element antenna, but theoretically:
            4 element dipole co-linear antenna gain = 5 dBi
            8 element dipole co-linear antenna gain = 8 dBi

            However, with increasing elements, the antenna becomes more directional in horizontal direction, but this is not a problem for ADS-B application, as the distance to planes reduces & consequently signal strength increases, when planes are very close to antenna location.
            Please see attached picture for directional patterns of a 1/2 wave dipole,a 4-element (4 x 1/2 wavelength) Franklin co-linear dipole, and an 8-element (8 x 1/2 wavelength) Franklin co-linear dipole antennas.

            Franklin-Co-Linear-Antenna-Directivity.gif
            Last edited by abcd567; 2013-09-25, 17:53.

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            • #81
              Does the same rule apply here: for every 3dB antenna gain, the received signal (power) doubles? Know with transmitting in FM bands, it is a rule of thumb.
              In your opinion: Shall I upgrade my 8 element co-linear to 12 element, or shall I attempt to build an 8 element Franklin co-linear?

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              • #82
                I just added one of those 13-18db in line antenna amplifiers ... I think it added 10-15% to the range - I now also have the brackets to replace my wall mounted 2m mast with about 5m ... should get it above the mine and neighbours roofs. Just need a dry W/E

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                • #83
                  Originally posted by HermanZA View Post
                  Does the same rule apply here: for every 3dB antenna gain, the received signal (power) doubles? Know with transmitting in FM bands, it is a rule of thumb.
                  In your opinion: Shall I upgrade my 8 element co-linear to 12 element, or shall I attempt to build an 8 element Franklin co-linear?
                  "For every 3dB antenna gain, the received signal (power) doubles" is not a rule of thumb, but a precise mathematical formula, as shown below:
                  Gain in dB = 10 x log (P2/P1)
                  If power doubles (i.e. P2/P1 = 2), Gain = 10 x log (2) dB = 10 x 0.30102999566 dB = 3.0102999566 dB ≈ 3 dB

                  Regarding your question "Shall I upgrade my 8 element co-linear to 12 element, or shall I attempt to build an 8 element Franklin co-linear?", I suggest that you try both and compare the results.

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                  • #84
                    Originally posted by peterhr View Post
                    I just added one of those 13-18db in line antenna amplifiers ... I think it added 10-15% to the range - I now also have the brackets to replace my wall mounted 2m mast with about 5m ... should get it above the mine and neighbours roofs. Just need a dry W/E
                    These in-Line amplifiers require 15 - 18 V DC to power them. This DC power is supplied either by the Receiver itself, or if the receiver does not have the provision to supply DC power to the antenna LNB or in-Line Amplifier, then a BIAS-T + A DC Supply (110V AC to 15 or 18 V DC Convertor/Adapter) is to be added.

                    What Power Supply arrangement for in-Line amplifier are you using? Does your receiver has the provision for it?

                    Since my receiver does not have the provision of DC 15V Supply to in-Line Amplifier, I have Designed & Built a DIY Bias-T.
                    Please see attached picture for my Power Supply arrangement.

                    Picture 1 : BIAS-T + Demuxer + in-Line Amplifier #2.
                    Picture 2 : DVB-T SDR USB Receiver connected to Desktop Computer.
                    Picture 3 : 4-Element Franklin Dipole Antenna + in-Line Amplifier #1.

                    DSC02543C.GIF DSC02555C.GIF DSC02576-R90c.jpg
                    Last edited by abcd567; 2013-09-25, 19:27.

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                    • #85
                      I'm using a small 5$ power injector - my collinear antenna is open ended (no resistor at the end) so the power by-passing the amp is not an issue.
                      The receiver (raspberry pi) is is now on wifi - which means when I get to move it to a sealed box under the eaves - it will just need the antenna + power connectors. Now the Pi is running off a low cost 12v (8v-20v in reality) power regulator. I can use the same supply to do the Pi and the amplifier - not done it yet though ... seems daft but it was easier to find a second PSU than to find a 2 core length of cable (but I do have a reel of house alarm connect wire in the shed )

                      Both the pi and the amp are presently running off 12v supplies. The amp looks identical to yours but is labelled FC-AMP-SAT/S and the power says 15v +- 3v

                      My Pi link in my footer should show it working.
                      Last edited by peterhr; 2013-09-25, 19:30.

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                      • #86
                        Originally posted by peterhr View Post
                        I'm using a small 5$ power injector .....
                        When I clicked your Raspberry Pi Link I was amazed.
                        Wow! you got an amazing coverage.

                        In my post, I have used the term "Bias-T" for which you have used the term "power injector".
                        I could not find a cheap "Bias-T/Power Injector", so I designed & built a DIY home-brew Bias-T/Power Injector. I added to it one more component to act it as "Demuxer" also, for combining outputs of 1090 MHz antenna & FM/Air Band VHF indoor Whip antenna to one cable to the Receiver.

                        Physical layout of my setup can be seen from the pictures in my previous post.
                        I am Attaching a schematic diagram of my setup with this post.

                        BIAS-T-02.jpg
                        Last edited by abcd567; 2013-09-25, 23:12.

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                        • #87
                          The power inserters are sold for use with DVB-T (Digital Video Broadcasting — Terrestrial, used in Europe ... you have ASTC) in-line amps could explain why they're easy to find here on amazon.co.uk or ebay.co.uk

                          Found one http://www.amazon.com/Inserter-power...llite+inserter

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                          • #88
                            Originally posted by North Borneo Radar View Post
                            Fingers crossed you get good news about it. Perhaps sending a picture to them showing the tower might help?
                            I was just approved!

                            Congratulations, your application to host ADS-B equipment from Flightradar24 has been approved.

                            We're now arranging to send you the ADS-B equipment and we will provide shipping details as soon as possible. Usually it takes about one week between a location being approved and the equipment being sent.


                            The antenna will be mounted on an arm off the left side of the tower top. This will place the antenna 650 feet above sea level and 150 feet above the Toronto (YYZ) Airport that's 16 Km away. The antenna will also be wired with LMR-400 (RG-8) cable which has only 1/4 the loss of RG-58 @ 1000 MHz

                            http://akn-systems.com/tower2/img_3718.htm
                            www.ADS-B.ca

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                            • #89
                              Good work. Just keep it away from that cellular panel below it lol
                              Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                              • #90
                                Originally posted by Oblivian View Post
                                Good work. Just keep it away from that cellular panel below it lol
                                It's not cellular, that's a radio for the round dish antenna... a 5.3 GHz data link.
                                www.ADS-B.ca

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