I have determined a way to feed four dipoles to provide good horizon to
horizon coverage at all angles for circularly polarized signals. It works
quite well for Low Earth Orbiting satellites. I lack the skills needed to
analyze the concept. I would like to make this concept available to anyone
who wants to build their own antenna.
I have a working model that seems to have no serious minimums when
receiving NOAA satellites at 137 MHz. The concept is quite simple and
probably easily understood by any antenna engineer.
Does anyone know where I might locate someone who would have interest in
knowing about this antenna concept that I have chosen to call the Cross
concept.

Jerry KD6JDJ

What did you have in mind? Do you want to profit from the idea, or
just make it freely available? Just what help (if any) are you looking
for: help with analysis, help with writing a description, help with
promoting it, help reviewing the idea and comparing and contrasting it
to previous ideas, or what? There are lots of folk here who could
potentially have an interest, and some even have a deep enough
understanding of antennas that they might actually be able to help.

Cheers,
Tom

Is it something like the Lindenblad?

http://www.phys.unsw.edu.au/~map/wea...indenblad.html

I'm always interested in an antenna design. Making some drawings or
taking some photos (or both) and putting them up on a website with some
measurements is a fine way to publish your construction.

If you are trying to make some money, I can help for some percentage to
be decided :-)

Seriously, though, everyone would be interested in the concept. Put it
up on a webpage, even if just a couple of photos. I think QSL.net and
some other sites will give you hosting.

73,
Dan
N3OX
www.n3ox.net

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

wrote:
Is it something like the Lindenblad?

http://www.phys.unsw.edu.au/~map/wea...indenblad.html

I'm always interested in an antenna design. Making some drawings or
taking some photos (or both) and putting them up on a website with some
measurements is a fine way to publish your construction.

If you are trying to make some money, I can help for some percentage to
be decided :-)

Seriously, though, everyone would be interested in the concept. Put it
up on a webpage, even if just a couple of photos. I think QSL.net and
some other sites will give you hosting.

73,
Dan
N3OX
www.n3ox.net




I believe this idea has already been done and used at major airports for
VHF communication. The ones I have seen have 4 dipoles on stalks, and
each is 45 degrees from horizontal. They are used for aircraft in closs
proximity to the field where polarization is unpredictable as craft
enter, leave, and cross over the strip.

"BKR" wrote in message
...


wrote:
Is it something like the Lindenblad?

http://www.phys.unsw.edu.au/~map/wea...indenblad.html

I'm always interested in an antenna design. Making some drawings or
taking some photos (or both) and putting them up on a website with some
measurements is a fine way to publish your construction.

If you are trying to make some money, I can help for some percentage to
be decided :-)

Seriously, though, everyone would be interested in the concept. Put it
up on a webpage, even if just a couple of photos. I think QSL.net and
some other sites will give you hosting.

73,
Dan
N3OX www.n3ox.net




I believe this idea has already been done and used at major airports for
VHF communication. The ones I have seen have 4 dipoles on stalks, and
each is 45 degrees from horizontal. They are used for aircraft in closs
proximity to the field where polarization is unpredictable as craft enter,
leave, and cross over the strip.

Hi BKR

That airport antenna is probably a Lindenblad. It has a serious "lack of
sensitivity" toward zenith. That "null straight up" isnt important at an
airport.
I submit to you that, although this Cross concept is basic and simple,
nobody has yet documented *anything* on it. The Quadrafilar Helix has the
same general pattern characteristics as the Cross, but the Helix is alot
more difficult for me to build and understand. In addition, the Cross can
be made to have considerably more sensitivity toward the horizon than the
Quad Helix.

Jerry

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