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Thread: best antenna

  1. #1801
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    On the antenna topic, interesting to find a seller on ebay that sells all the different types of antennas for ADS-B

    http://www.ebay.com/sch/stanislavpal...p2047675.l2562

    Any comments, experience with any of these ?

  2. #1802
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    Quote Originally Posted by HermanZA View Post
    On the antenna topic, interesting to find a seller on ebay that sells all the different types of antennas for ADS-B

    http://www.ebay.com/sch/stanislavpal...p2047675.l2562

    Any comments, experience with any of these ?
    His prices are very good... £15 delivered to the UK ! I couldn't make them at that price...

    Seems pretty honest with the gain figures too... he (?) states:
    Gain 2,3 Dbd

    Note this is Dbd.... which is gain over a dipole, not Dbi - which is an imaginary perfect antenna... this measurement is frowned upon in the Amateur radio world as it always offers a higher gain figure !

    As with anything antenna... the hardware and making the thing weatherproof is the hard bit - the antenna proper is going to be a few pennies worth of copper wire.

  3. #1803
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    24 hours Trial Run results
    (1) Antenna under test:
    4-element coco made of RG6 FPE VF=0.83 element length=114
    NO impedance matching arrangement
    NO amplifier
    Connected to receiver+Laptop with 20 ft/6 meter commercial RG6 coax.
    CoCo-4-Element-RG6-114mm-24hrs run-30 Oct 2014-R1.jpg


    (2) Benchmark
    Cantenna (Coke Can) + Amplifier
    Connected to receiver+Desktop with 50 ft/15 meters commercial RG6 coax
    BENCHMARK-1-Cantenna+Amp+50ft 15m Coax to Desktop-24hrs run-30 Oct 2014-R1.PNG


    Now on trial run: same CoCo as above, but 57mm shorted-top element added at top
    Last edited by abcd567; 2014-10-31 at 05:47.

  4. #1804
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    24 hrs trial run with 1/2 shorted element (57mm) added to 4 element coco of previous post #1800
    Range reduced instead of increasing!! The Dark Art of CoCo Making

    1/2 element added
    DSC03399-R.jpg

    Range of antenna under trial
    CoCo-4-Element-RG6-114mm-24hrs run-31 Oct 2014-R1.jpg

    Range of benchmark antenna
    BENCHMARK-2-Cantenna+Amp+50ft 15m Coax to Desktop-24hrs run-31 Oct 2014-R1.PNG

  5. #1805
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    abcd567, first of all thank you very much for your explanations and tutorials.
    How do you connect DC power supply to the splitter? You use DC socket, but how do you make the wiring?

  6. #1806
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    Quote Originally Posted by ozanguven View Post
    abcd567, first of all thank you very much for your explanations and tutorials.
    How do you connect DC power supply to the splitter? You use DC socket, but how do you make the wiring?
    Please see self-explanatory photos below.

    Before connecting/soldering coax to DC Barrel Jack, first check polarity on Barrel Jack (i.e. which terminal is positive, which is negative).

    To check polarity, plug-in the adapter in power socket, plug in the adapter's barrel pin into barrel jack, then with a multimeter check voltage and polarity of barrel jack terminals. Normally there are 3 pins. One of these will not show any voltage. leave that pin unconnected. Use the other two pins across which you get DC voltage. Normally center of the barrel pin & barrel socket are positive (+).

    DSC03411-R.jpg . DSC03412-R.jpg

  7. #1807
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    4-element CoCo with impedance matching.
    Twin-wire transmission line piece (40 mm long) inserted between bottom element & feed line.
    DSC03414 - R.jpg


    How I determined the length of twin-lead TL?
    Starting point was 4-element's impedance: 180-j180 ohms (from simulation by 4nec2 software).
    Rest is only for those interested in maths & theory (see picture below).
    DSC03417-R.jpg
    Last edited by abcd567; 2014-11-04 at 10:31.

  8. #1808
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    Hi ab cd,

    Wow, protractor and compasses . I haven't used those since I was at school many years ago. I've seen the Smith chart in various documents but had no idea what it was used for.

  9. #1809
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    18 hrs trial run results.
    4-element CoCo with impedance matching by twin-lead transmission line section.
    Twin-lead transmission line piece inserted between bottom element & feed line.
    Result: Improved Performance

    The twin-lead length:
    Calculated = 41.6 mm
    Initial trial length = 40 mm
    Finally adjusted for best result = 44 mm

    In order to be sure that good performance is not due to favorable weather conditions, I have put the CoCo & Benchmark antenna on 2nd round of 24 hrs trial run.

    CoCo under Test
    DSC03420-R.jpg


    CoCo Range plot (18 hrs trial run)
    CoCo-4-Element+42mmTL-RG6-114mm-18hrs run-03 Nov 2014.jpg


    Benchmark Antenna Range plot (18 hrs trial run)
    BENCHMARK-4-Cantenna+Amp+50ft 15m Coax to Desktop-18hrs run-03 Nov 2014-R1.PNG
    Last edited by abcd567; 2014-11-04 at 07:44.

  10. #1810
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    2nd Round of 24 hrs trial run - Good Performance
    4-element CoCo with impedance matching by twin-lead transmission line section.


    Good result in 2nd trial eliminates favorable weather conditions as the reason for good results.

    Next step: Test reproducibility in DIY environment.
    (1) Make another CoCo with same tape-measure & same coax (RG6 from same reel), and put to trial run.
    (2) Make another CoCo with same tape-measure, coax RG6, but from another manufacturer, and put to trial run.


    CoCo Under Test
    DSC03420-R.jpg


    CoCo Range plot (24 hrs 2nd trial run)
    CoCo-4-Element+42mmTL-RG6-114mm-24hrs run-04 Nov 2014.jpg


    Benchmark Antenna Range plot (24 hrs 2nd trial run)
    BENCHMARK-5-Cantenna+Amp+50ft 15m Coax to Desktop-24hrs run-04 Nov 2014-R1.PNG
    Last edited by abcd567; 2014-11-04 at 18:19.

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