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Thread: best antenna

  1. #2491
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    Quote Originally Posted by abcd567 View Post
    .
    Has anyone seen this site?

    http://global.adsbexchange.com/Virtu...r/desktop.html (ZOOM OUT TO SEE WHOLE OF NORTH AMERICA AND EUROPE)

    http://www.adsbexchange.com
    .
    They're using netcat to stream beast format data from port 30005 directly. It's kind of heavy on bandwidth compared to the other feeders. My average TX data for all three other feeders is around 7-8 kb/sec, whoch goes up to over 24 kb/sec. They need to figure out a more efficient way to get contirbution feeds, methinks!
    T-VABB7 | RTL dongle + Raspberry Pi + dump1090 + Bulgarian 5dBi collinear

  2. #2492
    Captain abcd567's Avatar
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    EXAMPLES OF FAILURE OF SIMULATION SOFTWARE
    Most of Collinears posted on internet are flawed design. These collinears are shown to be high gain by posting the supporting results of simulation. Almost no one posts results of actual measurements of Gain & SWR, or results of comparison with a standard benchmark antenna of known parameters.

    It is my experience that these simulation software give results with errors which may be of the order of 5% to 10%, which is too high for accurate optimization of collinears. To highlight this, I optimized wire collinears by simulation, and calculated parameters of these collinears and a 1/4 wavelength (non-collinear) benchmark antenna. I then made prototypes and put on trial run with reference to benchmark antenna.

    Results after optimization by simulation software were:
    Benchmark antenna - Standard Cantenna: Gain = 1.48 dBi, SWR = 1.28
    Antenna Under Test 1 - Coiled Cantenna: Gain = 2.99 dBi, SWR = 1.17
    Antenna Under Test 2 - Franklin Cantenna: Gain = 3.13 dBi, SWR = 1.9

    The simulation results show that both the Antennas Under Test should give better performance than Benchmark antenna. However when I made the prototypes using optimized dimensions given by simulation, and put on trial, results were opposite. This proved the unreliability of simulation results. I will now try to find the optimum dimension by trimming the prototypes.

    I have actually made 2 whips under test only, and simply pulled out the 1/4 wavelength (69mm) whip of existing Standard Cantenna and inserted in its place the Whip under test. This made all other factors identical for the benchmark & under test antennas.

    Prototypes (top to bottom):
    Standard Cantenna, Coiled Cantenna, Franklin Cantenna










    Simultion (top to bottom):
    Standard Cantenna, Coiled Cantenna, Franklin Cantenna









  3. #2493
    Captain abcd567's Avatar
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    The 4nec2 & mmana-gal softwares give large error for complicated antennas involving curved radiating wires/surfaces like coils of the collinear whip & shield of coco. Therefore for these antennas, the impedance value given by simulation have substantial error. Hence basing impedance matching capacitor & TL value on these values again gives poor results, and large number of trial & error attempts are required, which is tedious.

    The Franklin whip consists of only straight sections of wire, hence error is not large. In my opinion, the reason of poor performance of Franklin Cantenna is not wrong optimized dimensions. Rather it is due to SWR which is nearly 2, while 1/4 wave whip has SWR 1.3, and this difference in SWR results in Franklin Cantenna performing inferior to Standard 1/4 wave Cantenna.

    Anyway I will make & try the "Transmission Line + Capacitor" impedance match shortly and come back with the results, may be success, may be failure.



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  4. #2494
    Captain abcd567's Avatar
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    Impedance matching calculated by Smith Chart, then followed by trial run and trimming

    I have installed Impedance matching for Franklin Cantenna by "coax+capacitor" as shown in diagram in my last post above. I tried 3 lengths of coax: 85 mm, 80 mm, and 75 mm.

    The left-most part of graph is for the period when Cantenna had 1/4 wavelength (69 mm) whip. I then replced 1/4 whip by Franklin whip, and you can see drasticdrop in performance. I then inserted Impedance matching 75 mm coax +2.7 pF capacitor, then after about 15 minutes, changed piece of coax by 80 mm coax, then again after 15 minutes, changed piece of coax to 85 mm coax. As you can see best results are are 80 mm coax piece, as calculated by Smith Chart, very promising.

    I did not have 3 pF capacitor, so I have used 2.7 pF capacitor available with me. May be using aslightly higher or lower value of capcitor will gurther improve the performance. Someday,Iwill visit our local electronics & hobby shop and purchase many different values of capacitor in 0.5 pF to 10 pF range, and prrform trial and error again, this time keeping piece of coax fixed to 80mm, and changing the capacitor value between 1pF and 4 pf insteps of 0.5 pF.

    Below is rrd collectd graph which shows the results.






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  5. #2495
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    Captain - sorry don't know your real name - thanks for some great posts, I can see you appear to spend a lot of your time making, testing and retesting home made antenna's for us so I wanted to share a small bit of technical data with you I got from a friend in the UK Army - he is what he refers as a 'Field Radio Operator' although officially I think his title is something like 'Field Communications Analyst'!!!

    So, was talking to him about my limited knowledge of building Antenna's for ADS-B and guys like yourself that appear to thrive on it and he gave me the following information.

    With any vertical Antenna constructed, you can achieve a better signal if you use 1/4 wave radials (4) on the Antenna regardless of whether it is Full Wave, 3/4, 1/2, 5/8, or 1/4. He said this is also true if you are making a collinear antenna. It appears they have to cover (as part of their training) the ability to construct their own antennas in the field of operations in case their equipment is lost, damaged or destroyed, including Infra Red Transceivers, Satellite Dishes etc.

    In relation to 'cantennas', he advised that if you take the top and bottom off the can, flatten the can and cut to 1/4 wave on each side to a square then fit the Vertical or collinear antenna in the middle, you should get better results. I don't know the accuracy of this, he could be winding me up, but I thought it worth a mention....
    If life is a stage, most of us are unrehearsed...!

  6. #2496
    Captain abcd567's Avatar
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    @DemonLee
    The best way to find out is to make two antennas. One antenna as your friend has told you, and another one a Cantenna. Install one, leave it to run for say 24 hrs, and check your flightradar24 statistics to find maximum range it got. Then replace first antenna by second antenna and let it run for 24 hrs, then again check your flightradar24 statistics to find maximum range. The antenna which gives bigger maximum range is better.

  7. #2497
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    Quote Originally Posted by abcd567 View Post
    @DemonLee
    The best way to find out is to make two antennas. One antenna as your friend has told you, and another one a Cantenna. Install one, leave it to run for say 24 hrs, and check your flightradar24 statistics to find maximum range it got. Then replace first antenna by second antenna and let it run for 24 hrs, then again check your flightradar24 statistics to find maximum range. The antenna which gives bigger maximum range is better.
    You read my mind, was thinking of making 2 Cantenna, one as you show in your work, one by his method, then 2 vertical 1/2 waves, one with 1/4 wave radials, one without. Will have to wait until after the Xmas New Year Break now, but once done will need to do some testing.

    Have issue with ADSB# at the moment, receiving loads of data, but aircraft not showing in VirtualRadar

    This is my current range with the FR24 Box & Antenna, location is 176m ASL with a 5M mast on roof, kit is located at base of mast with 20m run of Power and Cat5 to the computer in my apartment. Frequently hit 250-350nmi to the South West over the Med into North Africa.
    5M Antenna Mast @ 181m ASL.jpg
    Last edited by DemonLee; 2015-12-19 at 07:08. Reason: added image
    If life is a stage, most of us are unrehearsed...!

  8. #2498
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    Hi you all,

    Can anybody do an abstract or summary with the best antennas?

    Reading all the 250 pages (and 2500 posts) of this thread is a hard job...Thanks to abcd567 and other users for their contributions


    Cheers.

  9. #2499
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    Quote Originally Posted by cannondale View Post
    Hi you all,

    Can anybody do an abstract or summary with the best antennas?

    Reading all the 250 pages (and 2500 posts) of this thread is a hard job...Thanks to abcd567 and other users for their contributions


    Cheers.
    (1) Coaxial Collinear (CoCo) is a high gain antenna, and requires a piece of coax to make. It is easy to make, but hard to get right. Most of the diy coco maker end up in frustration, as when they complete the antenna and put it to service, they get results far below what is claimed or expected. Only few lucky ones end up in making a successful coco.

    (2) Wire Collinear is a high gain antenna, and requires a piece of wire to make it, with wire wound into few turns of 1 or 2 coils between straight pieces of wire. It is easy to make, but hard to get right. Most of the diy wire colliear maker end up in frustration, as when they complete the antenna and put it to service, they get results far below what is claimed or expected. Only few lucky ones end up in making a successful wire collinear.

    (3) Franklin collinear is also a high gain antena, easy to make by a piece of wire, and cosists of stright sections of wire connected through hairpin shaped pieces of wire. Its also easy to make, but hard t get right. It is less tricky than coco and wire collinear, and is less difficult to get right. Again few lucky ones end up with a good Franklin.

    (4) The 1/4 wavelength monopole with ground plane (Spider & Cantenna) are low gain antenna, but very easy to get right, and most diy make successful Spider / Cantenna. I therefore recommend these for beginners. Its low gain can be easily covered by using a satellite tv in line amplifier.

    Once the begginner's system is up an running successfully with these simple & reliable 1/4 wave antennas, he can try his luck with collinears.

    Please see this thread for easy antennas fo beginners:

    3 EASY ANTENNAS FOR BEGINNERS

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    Last edited by abcd567; 2016-01-06 at 00:29.

  10. #2500
    Passenger cannondale's Avatar
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    Thank you.

    In my location, the antenna should resist high speed winds (around 100 km/h) and be weatherproof. In addition, I'm close to the sea and any metallic part gets rusted, so the canntena is not a good idea, or needs to be protected

    I'm thinking about making a CoCo, Slim Jim, J-Pole or Wire collinear and fit it in a PVC tube.
    Best ADS-B Antena resume here

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