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Re: lower frequency downlinks cont.



The optimal antennas for a HEO would just illuminate the earth with 1 dB
variation at apogee -- about 14 dB of gain at 35,000 km. However, you either
have to reduce the gain to allow for squint or be able to point the antenna.

73,

John
KD6OZH

----- Original Message -----
From: "Michael A. Tondee" <mat_62@netcommander.com>
To: <amsat-bb@amsat.org>
Sent: Tuesday, January 31, 2006 23:33 UTC
Subject: Re: [amsat-bb] lower frequency downlinks cont.


> Once again this is an opinion from the perpesctive of a "newbie" but I'n
not
> really understanding the concept of HF downlinks on an HEO. Seems
backwards
> to me and that  we should be going the other direction. The higher the
> frequency, the smaller the antenna can be physically which makes it much
> easier to build high gain beam and dish antennas which will be easier to
> rotate and have less wind resistance, at least from the ground station.
The
> satellite itself can also have superior antennas because they can be close
> to full size, if not full sized and be much more efficient. Just my
opinion.
> 73,
> Michael W4HIJ
> AMSAT #36017
> ----- Original Message -----
> From: "T. P. McGrane" <n2oeq@netzero.net>
> To: <amsat-bb@amsat.org>
> Sent: Tuesday, January 31, 2006 11:59 AM
> Subject: [amsat-bb] lower frequency downlinks cont.
>
>
> > Hello again, de pat n2oeq
> >
> > Thanks for the technical info and noise graph.
> >
> > My real world experience is that I hear HF downlinks better than VHF and
> > especially UHF.
> >
> > And I'm using a 12 element X beam for UHF and have marginal reception.
> >
> > I would love to build and launch a satellite but I dont have the
expertise
> > to do so. That is why I propose it to the group.
> > I'm happy to donate to amsat for a universally usable satellite but not
to
> > further the interests of a select few.
> >
> > Agree with the idea or reject it. If amsat is not interested, perhaps
they
> > could share it with other groups who might be interested.
> >
> > Many thanks to all the amsat volunteers for echo and eagle. Just think
> > about lower frequency downlinks in the future and PLEASE raise the Echo
> > downlink power on UHF PHONE now and then.
> >
> > K.I.S.S.  73, pat
> ----
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----
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