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Old February 10th 09, 04:47 PM posted to rec.radio.amateur.antenna
Art Unwin Art Unwin is offline
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Default Velocity Factor of Coax

On Feb 10, 1:57*am, "Jerry" wrote:
"Harry H" wrote in message

...





*The Lindenblad has an overhead null that you might find anoying for some
high elevation passes of LEOs.
*Are you open to trying to build a DCA (which is an antenna that I
developed)? * I make the claim that there is no other hemispheric
coverage antenna design that performs better than a DCA. * But, I sure am
open to being corrected.
*The Feb 2008 QST contains an article on the DCA antenna design concept.
*It is my claim that a DCA is extreemely forgiving of construction errors
and uses 4 wire dipoles and 50 ohm coax with 5 RFI type ferrites as
"baluns'.


* * * * * * * * * * * *Jerry * KD6JDJ

Given the fact I don't subscribe to QST, domicile Australia, would you
have a copy of the article?


HH


* Hi HH

* It would be my pleasure to disclose any/all the information I have
relating to the DCA antenna design concept. * It is simple. *It is two pairs
of crossed dipoles. * Each pair is spaced 1/4 wave apart and fed in phase.
One pair is physically mounted 90 degrees from the other pair. * All four
dipoles are tilted 30 degtrees from vertical. * One pair is fed 90 degrees
later than the other pair.
* The concept is so simple and straightfoeward that it is probable that the
concept has been developed before I thought of it. * But, I have been unable
to find anything published related to this simple "Double Cross Antenna"
* I told my *Internet buddy*, Patrik Tast, in Finland about the concept and
he found it to be exactly what he needed for reception of NOAA weather
satellite signals. * Patrik publishes alot of what I send him related to the
antenna. *Patrik shows a section of his web page to describe the DCA to
anyone interested. * You can find the QST article in the section Patrik
identifies as ANTENNAS on the first page of his sitehttp://www.poes-weather.com/index.php.

* If you have any questions about the DCA concept you are free to E-mail me,
anytime. * Or, if you have any facts or data to show where I am wrong about
how well this antenna performs, *or know of something that performs better,
please set me straight.

* * * * * * * Jerry * *KD6JDJ


Looked at the URL
What this antenna is doing is to aproach equilibrium by taking into
account the "weak force" which demands a tilting away from parallelism
or the verticle position away from the surface of the earth, without
which the radiation pattern will not be balanced.
When a U.S.naval base tipped all its verticle antennas at an angle
referenced to earth this prior null must have been of great
inconvenience with respect to defense alertness.