[amsat-bb] Re: Elk dualband antenna experiences

[David Palmer]

I'll add my two cents.

I've used the Elk exclusively for the last few months operating
"portable" in my backyard (and while camping, etc).  The Elk sits on a
photoraphic tripod, and I use a little netbook computer to display the
satellite plot and aim the Elk accordingly.  I absolutely love the
antenna, it assembles/disassembles quick, doesn't take up much space,
and has more than enough gain to work all the FM and SSB sats in this
configuration.

What I *have* noticed is that I do have to aim the Elk where the sat
is.  If I lower the antenna to horizontal, I notice a significant
fading.  That much is to be expected, so if you are in a situation
where you can't elevate the antenna, just aim it up a certain number
of degrees (maybe 15-30 depending on your horizon) so that it's close
enough for low passes, and the high passes (where sat is much closer)
should also work.

As for polarization, I've noticed that I get much better performance
out of the Elk by rotating the antenna to match the polarization of
the satellite at any given instant.  I have the PVC mount swivels
fairly loose, so it doesn't take much to flip the antenna back and
forth a little to find the best match.  When polarization is matching,
I can have better than S8 sigs, and rotating the polarization 90
degrees will often decrease my sigs to S2 or below.  So ... for a
fixed installation, with fixed polarization, you'll likely encounter
some deep fades in the passes, no matter which you choose.  So far
I've found that I typically use "almost vertical" polarization
compared to less frequently using "horizontal" polarization, so if I
had to choose between the two, I'd go vertical ... but it may not make
much difference!

One thing I've seen on the lists has been the recommendation to add a
pre-amp to the antenna.  Typically people will do this with an Arrow,
since it has separate VHF / UHF outputs so it's easier to config for
preamp.  Those that use this method report great results, since the
preamp overcomes much of the signal loss on the UHF downlink.  Since
the Elk has a single dual-band output, you may have to look into
duplexers to split out the UHF signal for the preamp.

Hope that helps!  That all being said, I've been putting together an
outdoor antenna system over the last few weeks (it's hard to sit in
the rain with the Elk and the twin FT-817's!) ... new system is a 4-el
VHF yagi and 15-el UHF yagi with preamps, on an az-el rotator.
Initial testing seems to indicate that it works pretty well -- so I'm
looking forward to staying dry during satellite contacts for a while!

73 de Dave KB5WIA / CM88

> -----Original Message-----
> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
> Behalf Of John Geiger
> Sent: Monday, December 20, 2010 7:43 PM
> To: Amsat-Bb at Amsat. Org
> Subject: [amsat-bb] Elk dualband antenna experiences
>
> How does the Elk Dualband yagi work as a satellite antenna in a base setup
> when you are not elevating it? Is it better to mount it for vertical or
> horizontal polarization to get maximum coverage of satellite passes?  Still
> trying to figure out the best FM sat setup here after some station redesign.
>
> 73s John AA5JG
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