Jerry Martes wrote:
I have determined a way to feed four dipoles to provide good horizon to
horizon coverage at all angles for circularly polarized signals.

Hi Jerry, how is your antenna superior to a two-dipole turnstile?
--
73, Cecil http://www.qsl.net/w5dxp

Hi Cecil

I'll top post to your question and the other repliers.

I have *NO* thoughts of money transfer. This is not an invention. I
merely assembled a set of four dipoles so they'd produce a pattern thats
sensitive to RHCP thruout the entire hemisphere. I'd probably even pay to
get someone to try building and testing one of these Cross antennas. I just
dont know what it is good for except receiving signals from NOAA weather
satellites.

The Double Cross does look alot like a Lindenblad. But, the dipoles are
tilted more sharply toward vertical.

Cecil, you ask about how this antenna differs from a turnstile. The four
dipole Double Cross has a pattern that has a much greater sensitivity to
RHCP toward the horizon than the turnstile. it even has sensivity to RHCP
at the horizon whereas the Turnstile is linear.

The fundamental concept (Cross concept) is two dipoles crossed at 90
degrees, both tilted from vertical, spaced about 90 degrees and fed in
phase. That produces circular polarization toward the horizon in two
opposite directions.
The Double Cross, which looks a little like the Lindenblad, is two Cross
antennas mounted together. One Cross is fed 90 degrees later than the
other.

I have been trying to develop this concept for more than a year and have
stumbled on a configuration that really works for receiving NOAA polar
orbiting satellite signals.
The GEO community has rejected the double Cross as its being "not
perfect". I dont know anyone else who'd have interest in an antenna thats
really easy to make and will work even when built somewhat differently from
some exact model.

A guy in England has been publishing all the NOAA satellite images I
record here in Los Alamitos. The images can be seen at
http://www.sattraxuk.com/imagestothe...ily/index.html

The images on this site begin and end at zero degree elevation of the
satellite, independent of the received signal strength. So, the viewer can
be assured that the images from this Double Cross are a good indication of
the sensitivity of the antenna and the amount of pattern nilling.

I have some text written to try to describe the concept. It is really
difficult for me to know if that text is understandable. Nobody has ever
asked me to clarify any of it. That is - I get no feedback. I just cant
find anyone interested in my project. Oh, I have located one guy who
thinks the Double Cross has merit. He is Patrik Tast, and lives in Finland.

So, if anyone has interest, or knows of anyone who'd like more info on the
Double Cross concept, I'd sure like to share this with them.

Thanks for the interest
Jerry
KD6JDJ 33.8 N 118.0 W


"Cecil Moore" wrote in message
. com...
Jerry Martes wrote:
I have determined a way to feed four dipoles to provide good horizon to
horizon coverage at all angles for circularly polarized signals.

Hi Jerry, how is your antenna superior to a two-dipole turnstile?
--
73, Cecil http://www.qsl.net/w5dxp

Jerry, can you post a photo on a webpage somewhere?

I think I get it... a single cross is like the driven elements of a
circularly polarized crossed yagi, the kind where you get the 90 degree
phasing by physical staggering of the elements.

Since it has no reflectors or directors, it's bidirectional. If you
cross two Crosses and feed them 90 degrees out of phase you get a
more-or-less omnidirectional azimuth pattern.

It is a pair of crossed dipoles fed as a turnstile.

I personally would probably still call it a Lindenblad, but maybe the
phasing is different on the Lindenblad.. I think they're phased the
same way, though.

Stick up a picture, if you can, or email to me... I'd like to see the
construction in case I'm missing something.

73,
Dan
N3OX

wrote in message
ups.com...
Jerry, can you post a photo on a webpage somewhere?

I think I get it... a single cross is like the driven elements of a
circularly polarized crossed yagi, the kind where you get the 90 degree
phasing by physical staggering of the elements.

Since it has no reflectors or directors, it's bidirectional. If you
cross two Crosses and feed them 90 degrees out of phase you get a
more-or-less omnidirectional azimuth pattern.

It is a pair of crossed dipoles fed as a turnstile.

I personally would probably still call it a Lindenblad, but maybe the
phasing is different on the Lindenblad.. I think they're phased the
same way, though.

Stick up a picture, if you can, or email to me... I'd like to see the
construction in case I'm missing something.

73,
Dan
N3OX


Hi Dan

The Lindenblad is quite alot different than the Cross. Perhaps my
objection to having the Cross being considered to be a version of the
Lindenblad is subjective. But, the two antennas are significantly
different from each other.

The Cross is not one particular antenna with exact dimensions. The
Cross is more a concept. When two Cross antennas are nested together, they
can be phased to provide sensitivity to circular polarized signals thruout
the hemisphere and have good sensitivity toward the horizon.

Jerry

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

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