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RHCP...

  • g7iii
  • Nov 20th 2018
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  • g7iii
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    Oct 28th 2018
    • Nov 20th 2018
    • #1

    Hi Guys,


    Can someone confirm for me...I know the uplink is RHCP. That means I need a LHCP feed right in the case of using a dish ? As my signal is bouncing off my dish...



    73s


    Iain

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  • DB8TF
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    • Nov 20th 2018
    • #2

    Correct

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  • g7iii
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    • Nov 20th 2018
    • #3

    In that case I have another bit of the required uplink bits...actually two...Even if they are a little large for small dishes, and likely to over illuminate! Now to find some way to mount them :)

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  • oh2aue
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    oh2aue
    • Nov 21st 2018
    • #4

    There is also a purpose-designed, high performance 2,4 GHz LHCP dish feed available from James, G3RUH:


    http://www.jrmiller.demon.co.uk/products/patch.html


    /Michael, oh2aue

    ---

    "If you have data, you have something, if you do not, you have nothing." (Bengt Hultqvist, SK 24.02.2019)

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  • DB8TF
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    • Nov 21st 2018
    • #5

    very expensive for something you can build on your own for a few buck..

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  • DD0KP
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    Dec 14th 2018
    • Dec 14th 2018
    • #6

    For those of you who want to buy an uplink antenna for a dish off the shelve I recommend the antenna from Winkler: http://www.winklerantennenbau.de

    38,70 Euro plus S&H


    DD0KP - Heiner - Waldkirch - JN38XC

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  • DL3DCW
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    • Dec 14th 2018
    • #7

    Thanks!

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  • ik4idy
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    xandrales
    • Dec 15th 2018
    • #8
    Quote from DD0KP

    For those of you who want to buy an uplink antenna for a dish off the shelve I recommend the antenna from Winkler: http://www.winklerantennenbau.de

    38,70 Euro plus S&H


    Wrote an email today, hope they'r able to read my questions, thanks. Regards.


    Alex

    IK4IDY

    Alessio

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  • DG8KD
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    • Dec 16th 2018
    • #9

    Hi,


    I also wrote an email to them a few days ago asking for LHCP and a slight shift of the frequency. Let´s wait for the answer.

    Here the direct link to the antenna (last one on the page):

    http://www.winklerantennenbau.de/heli12_15_24.htm

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  • ik4idy
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    xandrales
    • Dec 17th 2018
    • #10
    Quote from DG8KD

    Hi,


    I also wrote an email to them a few days ago asking for LHCP and a slight shift of the frequency. Let´s wait for the answer.

    Here the direct link to the antenna (last one on the page):

    http://www.winklerantennenbau.de/heli12_15_24.htm

    The helix normally is a very wide band antenna. This ant may be suitable for 2400 MHz. Okay is better to have an optimized helix, perfectly centerd on our band. But we told about 50 Mhz. with helix, not so far from our 2400 Mhz, isn't it ?


    Alex

    IK4IDY

    Alessio

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  • PA3FYM
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    • Dec 17th 2018
    • #11

    Also beware that short helices over illuminate 'standard satellite offset dishes'.


    A rule of thumb is that you need one turn per 0.1 'f/D'-unit.


    Standard BC-offset dishes have f/D's around 0.7, so you need 6 - 7 turns to get the right main lobe.



    Blue RHCP vs red LHCP (of course in front of a dish the helix
    has to be LHCP but in the NEC-model it's RHCP).

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  • DB8TF
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    • Dec 17th 2018
    • #12

    Here is an excellent PDF about helical feeds.


    http://www.w1ghz.org/antbook/conf/Helical_feed_antennas.pdf


    There he states that 4 turns are optimal for f/D 0,7..


    Now who is right ? :)


    VY73 DB8TF

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  • pe1chl
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    • Dec 17th 2018
    • #13

    It depends if you want to optimize for gain or for "spillover" which will result in extra noise when receiving (not what we are doing).

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  • F5MFO
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    • Dec 17th 2018
    • #14

    Hi guys,

    You may want to have a look to attached files, that I did find on the web.

    For this, you better have to learn french before, but this might do the job anyhow if you don't :-)


    The "calcul parabole ..." file allows dish performance estimation, as well as helix source turn number.

    The "HELICE" file contains an helix and matching device calculation.

    Enjoy !


    BTW, would be curious to knwo what "those who know" think about this matching style. Personaly, my knowledge is almost zero...


    73, Pat

    Files

    • HELICE.zip

      (814.75 kB, downloaded 390 times, last: Tuesday, 9:32 pm)
    • calcul parabole offset 10 Ghz ATV.zip

      (12.87 kB, downloaded 290 times, last: 18 hours ago)
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  • DB2OS
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    • Dec 17th 2018
    • #15

    Here another project for a combines S/X feed...


    Dual Band Coaxial Feed for Es`hail-2 Satellite from Rasto, OM6AA

    Peter Gülzow | DB2OS | AMSAT-DL member since 1983 | JO42VG

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  • pe1chl
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    Nov 4th 2018
    • Dec 17th 2018
    • #16

    That sure looks impressive! (both the device and the theoretical background)

    Not so easy to reproduce, I'm afraid.

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  • DJ7GP Peter
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    • Dec 18th 2018
    • #17

    Hello OMs,

    here you will find a duoband feed developed by me. This feed will be commercially produced and available early next year. When the distribution starts, I will announce this.


    https://www.darc.de/der-club/d…4/projekte-und-selbstbau/


    73! Peter, DJ7GP

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  • DJ7GP Peter
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    • Dec 19th 2018
    • #18

    Hi folks,

    here's a picture of the pre-production sample of my Duoband feed. Production starts in January.



    Peter, DJ7GP

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  • IW9EZO
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    • Dec 19th 2018
    • #19

    HI Peter.......how much for this nice dual-band ?

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  • ik4idy
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    xandrales
    • Dec 19th 2018
    • #20

    Hi,


    it's possible to have in 10 GHz polarization vertical and Horizontal ?


    TU

    IK4IDY

    Alessio

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    • dl4eax
    • Nov 20th 2018
    • Antenna
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