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CX2SA > SATDIG 20.09.08 22:12l 199 Lines 6011 Bytes #999 (0) @ WW
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From: CX2SA@CX2SA.LAV.URY.SA
To : SATDIG@WW
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Today's Topics:
1. More: circular polarization (45deg physical distance)
(Henk, PA3GUO)
2. Re: More: circular polarization (1/4wave physical distance)
(Henk, PA3GUO)
----------------------------------------------------------------------
Message: 1
Date: Sat, 20 Sep 2008 16:48:09 +0200 (CEST)
From: "Henk, PA3GUO" <hamoen(AT)iae.nl>
Subject: [amsat-bb] More: circular polarization (45deg physical
distance)
To: <amsat-bb(AT)amsat.org>
Cc: pa3guo(AT)amsat.org
Message-ID: <2402.212.61.85.20.1221922089.squirrel(AT)webmail.iae.nl>
Content-Type: text/plain; charset=iso-8859-1
So !
As the discussion is ongoing anyway:
This is how I have done it for 2 meters:
- 2 x 6 elements (phyically same position, no 1/4wave distance
http://www.pa3guo.com/dk7zb.html
- switch box for H/V/LHCP/RHCP in the shack (2 long cables needed)
http://www.pa3guo.com/polarizer.html
But now 70cm !
My 13 year old Cushcraft had always fixed circular polarization.
- 435.300 (AO51) had never any fading and was strong
- 435.150 (AO51) I could barely hear (proofs the >20 db separation)
Now: as AO51 will be in an mode that I want to use in the coming
days, with the 435.150 downlink, I needed to change the polarization.
Initially I wanted to have a temporal situation (swapping the
coax on the front dipol), but the screws needed replacement anyway,
so I decided to take the whole antenna down.
The 2x8 elements beam has the 2 antennas mounted 1/4 wave distance
spaced on the boom (the physical method).
Now, I want to be able to switch between LHCP and RHCP. Not fixed.
A good website I found is:
http://sv1bsx.50webs.com/antenna-pol/polarization.html
At the bottom the physical method for CP is described.
Almost what I needed, now I need to be able to switch on top of that.
I would assume that this should still be possible :-)
My preference would be only LHCP and RCHP, no need for Hor or Ver.
Prefer to have eg the coaxes of the 2 beams to a small relay box
on the back of the beam and then with a relais create the RHCP
vs LCHP.... but I lack the schematic for that :-)
... can someone point me to a URL that has the solution described ?
OR: would it be simply this:
1. take the front dipol
2. swap conductor/shielding to create LHCP or RCHP AT the solder points ?
(is this how WIMO is able to get it all in their small boxes)
Well, I have 2 days before AO51 is in the mode I requested,
I really need to get the antenna in place :-)
Thanks !
Henk, PA3GUO
http://www.pa3guo.com
------------------------------
Message: 2
Date: Sat, 20 Sep 2008 17:03:31 +0200 (CEST)
From: "Henk, PA3GUO" <hamoen(AT)iae.nl>
Subject: [amsat-bb] Re: More: circular polarization (1/4wave physical
distance)
To: <amsat-bb(AT)amsat.org>, <""(AT)iae.nl>
Cc: pa3guo(AT)amsat.org
Message-ID: <2460.212.61.85.20.1221923011.squirrel(AT)webmail.iae.nl>
Content-Type: text/plain; charset=iso-8859-1
Maybe my question becomes clearer with thse pictures (taken today)
1. this morning, the original set-up, on the roof
http://www.pa3guo.com/416_original.jpg
2. this afternoon, stripped, waiting for advice from the amsat-bb :-)
http://www.pa3guo.com/416_stripped.jpg
Henk
> So !
>
> As the discussion is ongoing anyway:
>
> This is how I have done it for 2 meters:
> - 2 x 6 elements (phyically same position, no 1/4wave distance
> http://www.pa3guo.com/dk7zb.html
> - switch box for H/V/LHCP/RHCP in the shack (2 long cables needed)
> http://www.pa3guo.com/polarizer.html
>
> But now 70cm !
> My 13 year old Cushcraft had always fixed circular polarization.
> - 435.300 (AO51) had never any fading and was strong
> - 435.150 (AO51) I could barely hear (proofs the >20 db separation)
>
> Now: as AO51 will be in an mode that I want to use in the coming
> days, with the 435.150 downlink, I needed to change the polarization.
>
> Initially I wanted to have a temporal situation (swapping the
> coax on the front dipol), but the screws needed replacement anyway, so I
decided to take the whole antenna down.
>
> The 2x8 elements beam has the 2 antennas mounted 1/4 wave distance spaced on
the boom (the physical method).
>
> Now, I want to be able to switch between LHCP and RHCP. Not fixed.
>
> A good website I found is:
> http://sv1bsx.50webs.com/antenna-pol/polarization.html
>
> At the bottom the physical method for CP is described.
> Almost what I needed, now I need to be able to switch on top of that.
>
> I would assume that this should still be possible :-)
> My preference would be only LHCP and RCHP, no need for Hor or Ver.
>
> Prefer to have eg the coaxes of the 2 beams to a small relay box
> on the back of the beam and then with a relais create the RHCP
> vs LCHP.... but I lack the schematic for that :-)
>
> ... can someone point me to a URL that has the solution described ?
>
> OR: would it be simply this:
> 1. take the front dipol
> 2. swap conductor/shielding to create LHCP or RCHP AT the solder points ?
>
> (is this how WIMO is able to get it all in their small boxes)
>
> Well, I have 2 days before AO51 is in the mode I requested,
> I really need to get the antenna in place :-)
>
> Thanks !
>
> Henk, PA3GUO
> http://www.pa3guo.com
------------------------------
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