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Thread: best antenna

  1. #2301
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    Hi All,

    I ordered a batch last month for the same source as Nic ordered them and they just arrived.
    These are the specs:

    SPECS
    1090MHz antenna
    Gain: 9dBi
    Connector: N-Female
    Output power: 100W

    ELECTRICAL SPECIFICATIONS
    Frequency Range: 1090MHz
    Impedance: 50 Ohm
    VSWR: Less than 1.5
    Gain: 9dBi
    Radiation: Omni
    Max. Power Input-watts: 100W
    Lightning protection: DC ground
    Horizontal Beam Width: 360 degree
    Vertical Beam Width: 14 degree

    MECHANICAL SPECIFICATIONS
    Height: 221420 mm
    Termination: N-Female
    Radome Material: Fiberglass
    Hold pole diameter: 25-40mm

    PM me if you want one. I know sending them to England from NL is expensive and is best done in a batch of 3 or more.
    The rest of Europe is reasonable!

    Ta Frank

  2. #2302
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    @JLD and abcd, i will try to get the parts to make the antenna during the week but I am away with work for a week this coming Monday so it may be a two weeks before i can get access to a VNA.
    T-EGLF8

  3. #2303
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    wire size ratio.png

    This table gives a good idea of the actual length an antenna should be in function of its 1/2 wave to wire diameter ratio.
    For 2mm the ratio is close to 70 at 1090 Mhz and requires a 6% shortening compared to 1/2 wave size (intersection between the curves and the 1/2 wave resonance vertical line)
    JL

  4. #2304
    Captain abcd567's Avatar
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    @JLD:
    Thank you for posting the length correction factor graph. Very useful & handy. What is the name of book from which this grapg is taken?

  5. #2305
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    RSGB radio communication handbook

    Preview: http://www.rsgbshop.org/acatalog/PDF..._12_sample.pdf

  6. #2306
    Captain abcd567's Avatar
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    Quote Originally Posted by JLD View Post
    RSGB radio communication handbook

    Preview: http://www.rsgbshop.org/acatalog/PDF..._12_sample.pdf
    Thank you very much.
    Googled & found 38 pages of chapter 16 at another location as well:

    http://lipcsey.gportal.hu/portal/lip...4047_02956.pdf

  7. #2307
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    with the spider franklin is this effectively what you are doing https://www.mikrocontroller.net/atta...2917/adsb2.gif by this i mean they are probably behaving in the same fashion

    i've made something along these lines and it worked quite well. Again like a spider one very easy to make and get right.
    Last edited by SpaxmoidJAm; 2015-04-11 at 10:29.
    T-EGLF8

  8. #2308
    Captain abcd567's Avatar
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    Quote Originally Posted by SpaxmoidJAm View Post
    with the spider franklin is this effectively what you are doing https://www.mikrocontroller.net/atta...2917/adsb2.gif by this i mean they are probably behaving in the same fashion

    i've made something along these lines and it worked quite well. Again like a spider one very easy to make and get right.
    Yes, both are wire collinears, but the difference is in Phasing arrangement - Coil vs Stub.

    Accuracy in both the design and construction are very important for collinear to give good performance.

    Few mm error in design or few mm error in construction knocks down collinear from excellent to poor.

    For both the design & the construction, it is much easier to be accurate with stub than with the coil.

    Franklin Spider.PNG . adsb2.gif . ads-b-1.jpg . adsb-3.jpg . adsb-4-rev.JPG
    Last edited by abcd567; 2015-04-12 at 05:14.

  9. #2309
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  10. #2310
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    which one is stub?

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