Are the differences physical, electrical or both?

I must be picturing the wrong setup if I'm conflating your design with
the Lindendblad.

You've mentioned the 137MHz Wefax antenna, and that one's not a
concept... can you pass along some construction details so I can get a
clear picture of it?

Dan

wrote in message
ups.com...
Are the differences physical, electrical or both?

I must be picturing the wrong setup if I'm conflating your design with
the Lindendblad.

You've mentioned the 137MHz Wefax antenna, and that one's not a
concept... can you pass along some construction details so I can get a
clear picture of it?

Dan


Hi Dan

Yeah, I can show you exactly how I built a Double Cross for receiving NOAA
satellite signals. A buddy of mine has chosen to publish everything I send
him.

http://213.250.83.83/~jerry/index.html

There is probably too much data on that site. The excess info and
pictures may get confusing.

Since you read this "antennas group", I'll assume that you may know as
much or more about antennas as I do. I dont claim to know *the best*
configuration of the Cross concept for APT reception. I do suggest that
four dipoles mounted so they are tilted slightly from vertical and spaced so
the diagonal dipoles are about 1/6th wave separated. can be easily fed to
provide RHCP toward the horizon and toward zenith. In the web site
http://www.amsat.org/amsat/articles/w6shp/lindy.html
The Lindenblad is described as an array of four dipoles tilted 30 degrees
from Horizontal and spaced 0.3 wave and all fed in phase.

The Lindenblad has a deep null straight up. The Double Cross has no null
anywhere in the hemisphere.

Thanks for the interest in the Cross. If you have any situation where
this hemispheric coverage with sensitivity to circular polarization, I'd be
interested in helping you design a Double Cross. All the Double Cross
antennas I've made seem to work well for receiving signals from the NOAA
polar orbiting satellites.

Jerry

Jerry,

OK, I'm getting more of an idea of the differences between the Lindy
and the Double Cross.

Well, I'm not particularly satellite-active right now, but I might have
to try one out sometime.

Keep up the experimentation... it would be cool to make a NEC model of
the thing, but I have EZNEC, currently without circular polarization
ability, so I can't do it.

I should try the Wefax thing sometime... that's pretty neat.

I think I have a TNC that can RX such transmissions.

73,
Dan
N3OX
www.n3ox.net