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Thread: pozitionare LNB

  1. #1
    Junior, da' cresc Mentor
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    Default pozitionare LNB

    imi poate spune si mie cineva cum se calculeaza pozitia LNB-ului fata de antena? cred ca al meu e pozitionat putin gresit si as vrea sa verific.
    Am o antena de 0.9m
    mersi!
    xyboox. Din Transilvania.

  2. #2
    Junior, da' cresc Mentor
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    ok, jumatate de problema am rezolvat-o, reusind sa-mi calculez distanta focala. Acum, singura necunoscuta ar fi pozitionarea lnb-ului in planul in care se afla distanta focala ( perpendicular pe antena ). Adica unghiul bratului lnb-ului ( ca la mine e pe un brat ). Stie cineva cum se calculeaza?
    Mersic!

    PS: antena e de 0.9 x 0.9
    xyboox. Din Transilvania.

  3. #3
    Junior, da' cresc Mentor
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    adica in imaginea de mai jos, cum stiu daca lnb-ul rosu, sau ala verde sau ala albastru e corect pozitionat?

    xyboox. Din Transilvania.

  4. #4
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    Default

    Ing. Jiri Otypka, CSc

    Calculating the Focal Point of an Offset Dish Antenna

    VHF Communications 1/1995

    It is assumed that readers know how to calculate the focal point of a symmetrical parabolic antenna. Offset antennae are a different matter. The popular belief here is that the focal point can not be established by simple means. However, this is not correct.

    To establish the focal point of an offset antenna, we need to measure three parameters instead of two: the large and small elliptical axes and the maximum antenna depth. The bulk of an offset antennae is formed by a three-dimensional space (Fig.1a). The similarity of offset antennae is determined by two parameters, but no explicit expression is available. The principle of offset antennae is described below, and the parameters and marginal conditions required to establish the focal point are given. A listing of a small BASIC program is also included, together with some checking calculations. ............


    vezi si tu


    http://www.vhfcomm.co.uk/otypka.htm

  5. #5
    Junior Member Teacher
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    sau

    http://www.qsl.net/n1bwt/chap5.pdf


    acolo si desene sunt m. multe

 

 

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