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
RHCP...
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Correct
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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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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
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very expensive for something you can build on your own for a few buck..
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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
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Thanks!
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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
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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):
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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):
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
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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). -
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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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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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
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Here another project for a combines S/X feed...
Dual Band Coaxial Feed for Es`hail-2 Satellite from Rasto, OM6AA
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That sure looks impressive! (both the device and the theoretical background)
Not so easy to reproduce, I'm afraid.
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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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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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HI Peter.......how much for this nice dual-band ?
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Hi,
it's possible to have in 10 GHz polarization vertical and Horizontal ?
TU
