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Re: Turnstyles or Egg Beaters?

An omidirectional antenna will only be useful with LEOs. I tried several
omnidirectional antennas for RS-10 and AO-16 in 1993 and simpler was better.
LEOs are below 30 degrees of elevation for most of the pass so you want an
antenna with most of its gain at low elevations.

Turnstile and eggbeater antennas are circularly polarized only at high
elevation angles where it isn't needed. A quadrifilar antenna has a null at
right angles so I wouldn't recommend it for LEOs unless you can rotate it on
at least one axis.

A Lindenblad antenna would better than either of the above. It is
omnidirectional and provides circular polarization at the horizon. The AMSAT
Satellite Experimenter's handbook has some information. However, it contains
4 dipoles so it is larger than a small yagi and won't please your neighbors.

A vertical antenna is almost as effective and less offensive to neighbors --
just make sure that it is 3 wavelengths or more above surrounding objects.
The ARRL Antenna Book has information on building 5/8-wave vertical, J-pole
and ground-plane antannas. The ground plane is trivial to build. Connect 4
wires to the mounting holes of the N or UHF connector and slope them down at
a 45-degree angle. The length is 492/F feet (F= frequency in MHz). Solder
the vertical wire to the center pin and make it 468/F feet long.

Mount a preamp at the antenna for the 2 meters and 70-centimeter bands.
Don't expect very strong signals from any of these antennas but you can make
some contacts.



----- Original Message -----
From: "Mike Tanner" <wb5nlj@home.com>
To: <amsat-bb@AMSAT.Org>
Sent: Thursday, 07 June 2001 00:30 UTC
Subject: [amsat-bb] Turnstyles or Egg Beaters?

> Hello everyone,
> I want to get in to satellite ops. I just got a Yaesu  FT-847 and want to
> put up some un-obtrusive omni-directional satellite antennas that don't
> attract a lot of attention.  My neighbors would not let me get by with a
> directional array, so my question is which are better?  Turnstyle, Egg
> Beater, or Quadrifflar?  And in that same vein, which are easiest for a
> so mechanically inclined" novice antenna builder to attempt?
> Thanks for your input
> 73's
> Mike WE3U (formerly WB5NLJ)
> mailto:wb5nlj@home.com
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
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