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  • ADS-B Splitter

    Can anyone recommend and preferably direct me to a source from where I can buy am ADS-B signal splitter. I am looking to split the feed from my external antenna to both a Puck and a Radarbox.

    Many thanks

  • #2
    Splitters are not high tech...

    they just match the impedance of the cables but there will some signal loss in using them, looking at a splitter now 5 to 1000Mhz has a quoted signal loss of 3.6 to 4dB (this was for Cable Broadband and TV) there are also lots of splitters for Satellite 5 to 2500Mhz around that cover 1090.

    As you are not transmitting so there is no power going up the cables how important is matching? yes there will be a loss of signal strength but is it going to be much worse than using a splitter?

    I have found a diagram for a DIY splitter but you will need some 75ohm cable to make your own.

    How to feed two 50 ohm Antennas from 50 ohm coax
    50ohms_2x_50ohms.gif
    http://dg7ybn.de/Phasing/Phasing.htm#50_to_75
    This was to combine two antennas but see no reason not to use as a splitter.

    Wavelength @ 1090Mhz = 275.2mm therefore 1/4 wavelength = 68.8mm

    Just a thought on splitting though be careful that both receiving devices have the same potential ground and they have blocking capacitors on the input and do not squirt out DC power to feed an aerial amplifier.

    Forgot to mention, splitters for Cable, TV and Satellite are normally 75ohm so you will need to match...
    Last edited by G8VXY; 2016-05-13, 07:44.
    """Learning is a treasure which accompanies us everywhere"""

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    • #3
      Originally posted by G8VXY View Post
      Splitters are not high tech...

      I have found a diagram for a DIY splitter but you will need some 75ohm cable to make your own.

      How to feed two 50 ohm Antennas from 50 ohm coax
      [ATTACH=CONFIG]7499[/ATTACH]
      http://dg7ybn.de/Phasing/Phasing.htm#50_to_75
      This was to combine two antennas but see no reason not to use as a splitter.

      Wavelength @ 1090Mhz = 275.2mm therefore 1/4 wavelength = 68.8mm
      Don't forget that the length will be quite different to this as you need to take the velocity factor of the cable into account.
      Depending on the cable you use you will need to multiple the length by anywhere from 0.6 to 0.95
      Ben.
      FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

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      • #4
        Originally posted by F-EGLF1 View Post
        Don't forget that the length will be quite different to this as you need to take the velocity factor of the cable into account.
        Depending on the cable you use you will need to multiple the length by anywhere from 0.6 to 0.95
        Ben.
        Opps...
        """Learning is a treasure which accompanies us everywhere"""

        Comment


        • #5
          While a Y-splitter will work, the best approach to maintain signal quality and provide isolation between ports, eliminating any potential noise feed through from the device antenna ports to each other, is to use a power divider/splitter. I find the MiniCircuits ZAPD-21 or similar on eBay all the time for $15 USD. They go for about $65 new.

          https://www.minicircuits.com/pdfs/ZAPD-21+.pdf

          Using this method you will not see the sort of loss typical of a Y-splitter at these frequencies.

          Remember if you use one that has more ports than are to be used at the moment, the empty port requires a 50ohm terminator plug.

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          • #6
            Originally posted by K5TED View Post
            While a Y-splitter will work, the best approach to maintain signal quality and provide isolation between ports, eliminating any potential noise feed through from the device antenna ports to each other, is to use a power divider/splitter. I find the MiniCircuits ZAPD-21 or similar on eBay all the time for $15 USD. They go for about $65 new.

            https://www.minicircuits.com/pdfs/ZAPD-21+.pdf

            Using this method you will not see the sort of loss typical of a Y-splitter at these frequencies.

            Remember if you use one that has more ports than are to be used at the moment, the empty port requires a 50ohm terminator plug.
            Looking at that PDF, you still get around 3.3db loss per port, they are just passive splitters, the only 'power' thing about them is that they have DC pass-through on both ports and can be used with a low powered transmitter (10w max) the loss would be the same as a well made 'Y' splitter.
            Ben.
            Last edited by F-EGLF1; 2016-05-17, 19:28. Reason: Corrections
            FR24 F-EGLF1, Blitzortung station 878, OGN Aldersht2, PilotAware PWAldersht, PlanePlotter M7.

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            • #7
              Originally posted by F-EGLF1 View Post
              Looking at that PDF, you still get around 3.3db loss per port, they are just passive splitters, the only 'power' thing about them is that they have DC pass-through on both ports and can be used with a low powered transmitter (10w max) the loss would be the same as a well made 'Y' splitter.
              Ben.
              The value is in the isolation between ports. If it's worth saving $15 to have all kinds of spurious noise being pushed between the two ports, Beverly Hillbilly style :-) , then go for the homebrew Y splitter.

              Seriously, though, professional radio practices both transmit and receive have a base in performance over expedience. The problem with using a simple Y with these types of receivers is the propensity for LO and other internal signals to find their way back out the antenna port and into the front end of the other receiver. These signals, particularly with different receivers on each port, can combine to create harmonics and other spurious junk that serves only to lessen the signal quality overall.

              The MiniCircuits splitters of various bandwidths and passbands are generally used on the test bench but can also be pressed into service for feeding multiple amplifiers with balanced signals.

              Hackaday lashups, while cost effective and fun, will never outperform conventional RF engineering practice. There are no 'black arts' in receive technology.

              Nigel seems to already have a considerable investment in his existing gear, and IMO, using high quality components in the signal chain is a given. The best receiver is only a doorstop without a good feedline.
              Last edited by K5TED; 2016-05-18, 13:25.

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              • #8
                Splitter

                Originally posted by Nigelr View Post
                Can anyone recommend and preferably direct me to a source from where I can buy am ADS-B signal splitter. I am looking to split the feed from my external antenna to both a Puck and a Radarbox.

                Many thanks
                Not cheap, but the best
                Stridsberg Engineering splitter, powered, no loss. from 2,4 or 8 ports. Good at 1.09GHz

                $185 for a 4 port

                I can recommend them.

                MCA204M
                VHF/UHF Receiver Multicoupler - 25 MHz to 1 GHz - 4 Ports NATO / NSN number: 5865-01-532-0314
                Last edited by radiosutch; 2016-06-07, 21:40.

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