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  • Bad antenna performance

    Hi,

    I installed a 1090MHz exterior antenna on my roof. I have a stainless steel chimney that isn't in use. I use it to feed the cable inside. The performance is really bad but if I push the cable against the chimney the range drastically improves to +-80nm. Anyone an idea what I can do to improve the performance further? With his antenna I expect +200nm.

    Cheers

  • #2
    Most likely problem: bad connectors or bad connection.

    Give more details about
    1. Antenna model and gain
    2. Coax (type and length)
    3. Connectors at both ends of coax
    4. Receiver i.e. is it a Flightradar24 supplied equipment or generic DVB-T or ProStick or Nooelec dongle.
    5. Which type of connector your receiver has?

    Comment


    • #3
      I did some additional tests: when the cable is not fed through the chimney I have a more consistent performance. (+-130 nm) When the cable is going through the chimney, I can manipulate the cable such that it has similar performance.

      Comment


      • #4
        Hi abcd567,

        I replied with some links so it's being moderated. Now without links:
        - Flightaware antenna
        - CO-100-AF 10m
        - N type connector -> SMA ( ->MCX)
        - Nooelec dongle (other imprint, same plastics) with MCX connector

        Comment


        • #5
          Originally posted by tintin View Post
          Hi abcd567,

          I replied with some links so it's being moderated. Now without links:
          - Flightaware antenna
          - CO-100-AF 10m
          - N type connector -> SMA ( ->MCX)
          - Nooelec dongle (other imprint, same plastics) with MCX connector
          You may need an Amplifier (or Amplifier+Filter), but first check what maximum you can get.

          What is the Maximum Range I can Get?

          Comment


          • #6
            Your cable CO-100-AF has an attenuation of 32 dB /100 m at 1000 MHz. As your cable length is 10 m, the attenuation is 3.2 dB. An amplifier will help.

            http://www.bieffecavi.com/pdf/CO100AFeng

            Screenshot_2017-12-09-21-39-58.jpg
            Last edited by abcd567; 2017-12-10, 02:52.

            Comment


            • #7
              Originally posted by abcd567 View Post
              You may need an Amplifier (or Amplifier+Filter), but first check what maximum you can get.

              What is the Maximum Range I can Get?
              Nice sticky you made
              I get an almost perfect circle with a radius of 260 miles. Or 225nm. So theoretically it must be possible to double the range I reach today.
              Do you think using a new r820t2 with tcxo will help (significantly)? Or another cable?
              Any suggestions for a good amplifier?

              Comment


              • #8
                Originally posted by abcd567 View Post
                the attenuation is 3.2 dB. An amplifier will help.
                That is NOT his main problem. Better to solve the problem before adding more variables to the equation.

                /M
                F-ESDF1, F-ESGG1, F-ESGP1, F-ESNK1, F-ESNV2, F-ESNV3 F-ESSL4, F-LFMN3
                P-ESGR, P-ESIA, P-ESIB, P-ESGF
                mrmac (a) fastest.cc

                Comment


                • #9
                  Did you waterproof the N-connector with proper self-sealing tape?

                  How high is the antenna over the chimney?

                  How is the antenna mounted galvanically, is it grounded to the chimney? Is the chimney grounded to any type of lightning protection?
                  are there other antennas like TV galvanically connected to the chimney?

                  Is the SMA-MCX a rigid adapter or a flexible pigtail?

                  /M
                  F-ESDF1, F-ESGG1, F-ESGP1, F-ESNK1, F-ESNV2, F-ESNV3 F-ESSL4, F-LFMN3
                  P-ESGR, P-ESIA, P-ESIB, P-ESGF
                  mrmac (a) fastest.cc

                  Comment


                  • #10
                    Originally posted by MrMac View Post
                    That is NOT his main problem. Better to solve the problem before adding more variables to the equation.

                    /M
                    thumbs-up-3.jpg

                    Fully agree!

                    Comment


                    • #11
                      Originally posted by MrMac View Post
                      Did you waterproof the N-connector with proper self-sealing tape?

                      How high is the antenna over the chimney?

                      How is the antenna mounted galvanically, is it grounded to the chimney? Is the chimney grounded to any type of lightning protection?
                      are there other antennas like TV galvanically connected to the chimney?

                      Is the SMA-MCX a rigid adapter or a flexible pigtail?

                      /M
                      Following photos will help us analyze situation:
                      (1) Photo of antenna showing surrounding
                      (3) Close-up photo of bottom of antenna, showing mounting and cable connection
                      (3) Photo of Nooelec Dongle showing antenna connection arrangement.

                      Comment


                      • #12
                        Originally posted by abcd567 View Post
                        Following photos will help us analyze situation:
                        (1) Photo of antenna showing surrounding
                        (3) Close-up photo of bottom of antenna, showing mounting and cable connection
                        (3) Photo of Nooelec Dongle showing antenna connection arrangement.
                        Here some pictures:
                        dongle.jpgantenna.jpg

                        The antenna has two wires: one coax and one copper wire twisted around the bar that connects the antenna to the chimney. I tried with/without but little or no difference in performance.

                        Comment


                        • #13
                          The photo of antaina shows you have applied tape over cable connector at base of antenna, so ingress of moisture is ruled out. Alse at dvb-t, there is no pigtail, nly a solid F-to-smx adapter, so bad pigtail is ruled out.

                          I feel the 3.2 dB attenuation of Coax is causing drop in performance. An amplifier is expected to improve the situation.

                          The amplifier can be an external aplifier+power inserter+dc adapter. A satellite amplifier for L band (950 - 2050 mhz). is a cheap solution.

                          Alternatively you can purchase a dvb-t with built-in amplifier which will not require any power inserter or dc adaptor. One such dvb-t is Flightaware's Pro Stick (Orange color):

                          https://www.amazon.com/gp/aw/d/B01D1ZAP3C

                          Please note that if there are strong mobile/cell phone signals in your area, you will have to reduce gain setting of dongle. Try different values of gain like 45, or 40 or 35 or 30. By default the gain is set to maximum which is 49.6.
                          Last edited by abcd567; 2017-12-11, 22:42.

                          Comment


                          • #14
                            Originally posted by abcd567 View Post
                            Alternatively you can purchase a dvb-t with built-in amplifier which will not require any power inserter or dc adaptor. One such dvb-t is Flightaware's Pro Stick (Orange color):

                            https://www.amazon.com/gp/aw/d/B01D1ZAP3C

                            Please note that if there are strong mobile/cell phone signals in your area, you will have to reduce gain setting of dongle. Try different values of gain like 45, or 40 or 35 or 30. By default the gain is set to maximum which is 49.6.
                            Thanks, I ordered the orange Flightaware dongle... I'll keep you updated...

                            Comment


                            • #15
                              Originally posted by tintin View Post
                              Thanks, I ordered the orange Flightaware dongle... I'll keep you updated...
                              Great!
                              Remeber you will have to reduce gain from default "max" (49.6) or default -10 (automatic gain control agc) to 45, then 40 then 35 then 30. For each value observer for a while maximum range and plane count. Finally use the gain setting which gives you best results.

                              The method to change gain depends on the software you have installed. Is your DVB-T plugged into a Windows PC or a RPi? What software you use?

                              Comment

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