Well, after I replied to you post I remembered another antenna type. The
reason I mentioned the Turnstile first is that it is easier to build. You
are right. The pattern does fall apart when you get into the same
horizontal plane as the antenna.

You have two choices. Either a highly directional antenna, for which you
would have to have a tracking system to follow the satellite, and the
appropriate software to run the thing (predicting when and where the bird
will appear).

The other choice, which is what I would recommend, is the quadrifilar helix.
It can be designed to have a hemispherical 180 degree beamwidth and still
have the same RHCP over entire beam. I would even suggest making it a bit
more than 180 degrees beamwidth, perhaps 200 degrees. The problem with the
quadrifilar helix is that it is harder to build than a simple turnstile, but
still easier than a directional antenna with two axis directional control.
A Google search gave 2860 hits for "quadrifilar helix". One I looked at was
http://web.ukonline.co.uk/phqfh/qfh.pdf . If you are not afraid of the
metric system, it gives detailed construction notes for a 137 MHz antenna
made from copper plumbing parts.

--
Jim
N8EE

to email directly, send to my call sign at arrl dot net

"Jerry Martes" wrote in message
...

Jim

I'd like to get RHCP on the horizon so I could "pick up" the satelite as
early as possible.

Jerry



"JLB" wrote in message
.. .
Do a web search for "Turnstile Antenna".

Jim
N8EE
"Jerry Martes" wrote in message
...
I'd like to build an antenna for receiving 137 MHz signals from
polar
orbiting NOAA weather satellites. I would like to get some
information
from
any of the readers of this group who might have thought about
designing
an
antenna for this application.

Jerry