[GreenKeys] OT: weather balloon telemetry

[Chris Elmquist]

There's also the "EggBeater",

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=23658

which would provide circular polarization too and would be a little
bit like a "bouncy ball" when hung underneath the balloon.

Chris N0JCF

On Tuesday (11/05/2013 at 04:05PM -0600), Chris Elmquist wrote:
> So, you are going to downlink on 2m?  144.390?
> 
> You might consider a crossed-dipole (sometimes referred to as a
> "turnstile") antenna which will give you circular polarization and
> reduce fade if the balloon is spinning.  It will be 3dB down from a
> linear polarized antenna on the ground but if there is any spin, it will
> not go through peaks and valleys as the two antennas go in and out of
> polarization alignment.
> 
> It will then also be "flat" on the bottom of the balloon (would look like
> a "+" as you look up at the bottom of the balloon) and then won't stick
> in the ground when it comes down but instead be a little like landing
> gear :-)
> 
> Here's one discussion,
> 
> http://www.west.net/~jay/turnstile.html
> 
> Chris N0JCF
> 
> On Tuesday (11/05/2013 at 08:49AM -0700), gil at baudot.net wrote:
> >    OK folks, after some good info from several of you, it does sound like
> >    using 144.390 MHz APRS tracking would be the best bet for this balloon
> >    project.
> > 
> >    This means I need to study for a ham test now, but they seem to be
> >    offered frequently enough, so I guess I will need to start learnin'
> >    some new stuff!
> > 
> >    Back to my question about antennas:  what to hang under the balloon?
> >    It has been pointed out how it needs to be omni.  I suppose the
> >    simplest would be a 1/4 wave hanging down, and suspended by three or
> >    four angled ground wires that connect to a simple
> >    three-or-four-radial-dowel frame or something.  The antenna would
> >    collapse on the ground (of course we hopefully have GPS coordinates for
> >    the descent, so we can find it).
> > 
> >    Any other antenna recommendations?  Dipole?  Patch?  Nothing commercial
> >    -- something I can fabricate out of lightweight wire or foil.
> > 
> >    thx,  gil
> > 
> >    gil smith
> >    greenkeys moderator
> >    [1]gil at baudot.net
> > 
> > References
> > 
> >    1. mailto:gil at baudot.net
> 
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> -- 
> Chris Elmquist
> 
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-- 
Chris Elmquist