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CX2SA > SATDIG 05.08.12 21:13l 170 Lines 6117 Bytes #999 (0) @ WW
BID : AMSATBB7247
Read: GUEST
Subj: AMSAT-BB-digest V7 247
Path: IZ3LSV<IR1UAW<IK1NHL<CX2SA
Sent: 120805/1903Z @:CX2SA.SAL.URY.SA #:64491 [Salto] FBB7.00e $:AMSATBB7247
From: CX2SA@CX2SA.SAL.URY.SA
To : SATDIG@WW
Today's Topics:
1. Re: Antenna Polarization Technical Question (Thomas Doyle)
2. Yubileiny-2 RS-40 (Jean-Pierre Godet)
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Message: 1
Date: Sun, 5 Aug 2012 08:30:29 -0500
From: Thomas Doyle <tomdoyle1948@xxxxx.xxx>
To: i8cvs <domenico.i8cvs@xxx.xx>
Cc: Amsat - BBs <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Antenna Polarization Technical Question
Message-ID:
<CAHnRQRLDFRnOqR4pRez33NeBj6hEggsT0iVGazX4=_H4WEaYbw@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Thanks to Domenico for sharing the work done by K4KJ. It is amazing
how much good information there is out there. It takes a bit of
digging to find it but it is worth the effort. The configuration shown
in figure 14 looks promising but probably too difficult to put on a
sat.
W9KE Tom Doyle
On Sat, Aug 4, 2012 at 10:18 PM, i8cvs <domenico.i8cvs@xxx.xx> wrote:
> Hi All,
>
> I agree completely with Bob, WB4APR and this is what is wery well
> explained into the article "CIRCULAR POLARIZATION by K4KJ,
> a zipped file 5 MB long available from me.
>
> 73" de
>
> i8CVS Domenico
>
> ----- Original Message -----
> From: "Bob Bruninga " <bruninga@xxxx.xxx>
> To: "Thomas Doyle" <tomdoyle1948@xxxxx.xxx>
> Cc: <amsat-bb@xxxxx.xxx>; "andrew abken" <kn6za@xxxxxxx.xxx>
> Sent: Sunday, August 05, 2012 12:24 AM
> Subject: [amsat-bb] Re: Antenna Polarization Technical Question
>
>
>> > Not sure why anyone would want to maintain the
>> > orientation of the satellite in such a way that
>> > would cause the direction of circular
>> > polarization to change during the path.
>>
>> Lets try this approach... As I said before, By the laws of physics, what
> comes out one side of a circular polarized low gain antenna as RHCP comes
> out the opposite side as LHCP.
>>
>> Now given that, and the fact that someone in Maryland is in the center of
> the RHCP beam, then by the laws of physics, the guy in California must see
> mostly LHCP. No matter how much one of those persons demands that he
> deserves the RHCP beam, by definition, someone else somewhere will get the
> LHCP one, and the geometry changes at least every 10 minutes or so and every
> time the spacecraft rotates a bit.
>>
>> So one might say, "point it down" then only the person in Kansas will see
> the main beam and those in CA or MD will be completely off the sides almost
> 70 degrees from the main beam. Mot people do not realize how LOW these
> satellites are. The only solution is to put satellites so high, that "down"
> is about the same to everyone (geostationary altitude). But then that takes
> 100 times more altitude, and that takes 10,000 times more power.
>>
>> Better to just live with the laws of physics... I guess.
>>
>> Bob, WB4aPR
>>
>> >
>> >On Sat, Aug 4, 2012 at 2:47 PM, Bob Bruninga <bruninga@xxxx.xxx> wrote:
>> >>> I believe that is true but that does not explain
>> >>> why the optimum polarity setting on the receive
>> >>> end would change during a pass.
>> >>
>> >> That's easy. The circularity on a pair of crossed dipoles (about all
> you can get on a spacecraft) May be designed for Right hand circularity when
> viewed from the prime direction. But by definition, that save waveform will
> be LHC when viewed from the opposite direction.
>> >>
>> >> And since the geometry to any one observer is constantly changing by
> almost 180 degrees during an overhead pass, that is why it is very easy to
> see, complete change in circularity.
>> >>
>> >> Bob, WB4APR
>> >>
>> >
>> >
>> >
>> >--
>> >
>> >Sent from my computer.
>> >
>> >tom ...
>> _______________________________________________
>> Sent via AMSAT-BB@xxxxx.xxx. Opinions expressed are those of the author.
>> Not an AMSAT-NA member? Join now to support the amateur satellite program!
>> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
>
--
Sent from my computer.
tom ...
------------------------------
Message: 2
Date: Sun, 5 Aug 2012 10:23:21 +0000 (UTC)
From: Jean-Pierre Godet <godetj@xxxxxxx.xx>
To: ans-editor@xxxxx.xxx
Cc: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Yubileiny-2 RS-40
Message-ID: <Pine.LNX.4.60.1208050840120.432@xxxxxxx.xxx>
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
Dear friends,
Thanks to Jean-Louis Rault F6AGR who quickly informed me, I heard my
first signal from Yubileiny-2 RS-40 on monday July 30th afternoon. The
signal of the 435.365 MHz beacon was fairly strong regarding my poor
receiving devices and aerials.
After that, the beacon was heard on 435.265, but more often on 435.365
MHz, sometime none of these two frequencies. I am using the 2012-041D
NORAD elements. I am not sure it is the good one, but for the moment A, B,
and C, the three others payloads launched with the same Rockot vehicle are
not too far away.
Trying to get information about the Yubileiny-2 satellite, I sent
inquiries about the telemetry and the possibility that may be one of the
beacons will move to CW as it was done with the previous Yubileiny-1 RS-30
and Mozhayets-4 RS-22, but I received no reply till now : three mails in
russian, to the Siberian State Aerospace University (RS-40 instruments and
research mission, Rrasnoyarsk), to ISS Reshetnev (company manufacturing
the RS-40 satellite, Krasnoyarsk), and to A. P. Papkov (Laboratory of
Astronotical technology, Kaluga, who published the telemetry decoding of
RS-22 and RS-30).
We are waiting with hope but, may be I am wrong, looks like the
university and the ISS company are not very interested by a collaboration
with the radioamateur community, only by their frequencies around 435 MHz.
73 !
Jean-Pierre/F5YG
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End of AMSAT-BB Digest, Vol 7, Issue 247
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