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1090Mhz atenna

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  • #16
    Thanks for the info, not sure exactly what this all means, trying to though, just want to put the attenna outside so i get better reception, indoors is not good.

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    • #17
      All cable has signal loss. Some more than others. The one you name will lose 4.42dB of signal every 25ft.

      If you have 25ft of cable to get it outside and on a roof that is 3dB of gain you have wasted. So if you have an external antenna of 9db on the end of it. it's effectiveness will be now less than 6 (as connectors also have a loss too)

      If you get high grade cable, this loss is a lot less. For instance LMR400 from memory is about .06dB/ft. Which means for that same 25ft length, you would only lose about 1.6dB
      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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      • #18
        Ok thanks Oblivian and digiteyes, understood now.

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        • #19
          Originally posted by Oblivian View Post
          All cable has signal loss. Some more than others. The one you name will lose 4.42dB of signal every 25ft.

          If you have 25ft of cable to get it outside and on a roof that is 3dB of gain you have wasted. So if you have an external antenna of 9db on the end of it. it's effectiveness will be now less than 6 (as connectors also have a loss too)

          If you get high grade cable, this loss is a lot less. For instance LMR400 from memory is about .06dB/ft. Which means for that same 25ft length, you would only lose about 1.6dB
          An active USB extention cable may be a good alternative to antenna cable. You can get a 50 ft. active cable for 30-50 USD or less. This means that instead of a long cable between the antenna and the USB dongle, you have the USB cable between the dongle and the computer. 'Active' means that there is a circute in the cable that will buste the signal.

          This means that you are also bringing the dongle outside and need to protect that too. You may go for a combination where you use a USB cable to bring the dongle up high inside the roof and then a shorter antenna cable to connect to the antenna on the outside.

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          • #20
            Originally posted by Kpin View Post
            An active USB extention cable may be a good alternative to antenna cable. You can get a 50 ft. active cable for 30-50 USD or less. This means that instead of a long cable between the antenna and the USB dongle, you have the USB cable between the dongle and the computer. 'Active' means that there is a circute in the cable that will buste the signal.

            This means that you are also bringing the dongle outside and need to protect that too. You may go for a combination where you use a USB cable to bring the dongle up high inside the roof and then a shorter antenna cable to connect to the antenna on the outside.

            Put your dongle in one of this outdoor weather proof box.

            ClosedBox.jpg
            F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

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            • #21
              Home-brew Antenna

              DSC02542B.GIF DSC02543B.GIF
              See attached Images for My Home-Brew System of Antenna, 2x 18 dB inLine Amplifiers, Home-brew DC 15V Power Injector (Bias-T). My Maximum Range = 450 Kilometers with indoor antenna (simple quarter-wave dipole - 2 arms, 6.8 cm each) + 2 in-line amplifiers in cascade as shown in these pictures.

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              • #22
                Home Brew Antenna -2

                My earlier home-brew antenna was really tiny & cute. It was 1/2 wavelength dipole consisting of two 1/4 wavelength arms, i.e a total of 2x6.8=13.6 cm, the tiniest antenna resonant at 1090 MHz. This antenna has a theoretical gain of 2 dBi.

                I have now built a "4-Element Franklin Co-Linear" dipole antenna with 5 dBi gain.
                It is a dipole, and has 2 arms, each arm is 2 x 1/2 wavelength tall.
                The total height of this dipole is therefore 2 x 2 x 1/2 wavelength = 2 x 2 x 1/2 x 27.2 cm = 54.4 cm.
                This antenna is 4 times taller than my tiny 1/2 wave dipole but has a gain of 5 dBi compared to 2 dBi of tiny dipole.

                In order to cover for attenuation of long coaxial cable, I have used 2 in-Line amplifiers (13-18 dB Gain each), costing $4 each amplifier.

                Please see attached pictures for my setup:
                Picture 1: DVB-T SDR USB Receiver connected to Desktop Computer.
                Picture 2: Power Injector (also called Bias-T) for injecting 15V DC in coaxial cable to power the in-Line Amplifiers.
                Picture 3: 4 x half-wave element Franklin Co-Linear Dipole Antenna.
                Picture 4: 1 x half-wave element basic Dipole Antenna.
                Picture 5: Schematic Diagram of the setup.


                DSC02555C.GIF DSC02543C.GIF DSC02576-R90c.jpg DSC02542C.GIF BIAS-T-02.jpg

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