DOUGLAS ZWIEBEL wrote:
>
> I bet this will add some punch to your Top Band QRP signal.
>
> http://www.ok1rr.com/news.php
>
> Scroll down a bit. It is difficult to imagine the scale, so read a
> little about it.
>
That will be an interesting experiment but I'm glad I'm not funding it!
There is data that suggests it may not work as well as one might expect
(i.e. a vertical array may be better). There's a unique aspect to 160
propagation called magnetic coupling loss which K9LA describes briefly in
his Polarization article:
"Again, as expected, the characteristic waves take different paths through
the ionosphere --
but the difference is significantly more on 160m because 1.8MHz is very
close to the
electron gyro-frequency (which varies from about 0.7 to 1.7MHz worldwide
depending
on the intensity of the magnetic field), which significantly modifies the
index of
refraction of the x-wave. And as we saw on 10m, the x-wave refracts more
than the o-wave.
The other obvious result is that the x-wave, over the same one-hop path,
suffers
significantly more absorption than the o-wave. Again, this is due to 1.8MHz
being very
close to the electron gyro-frequency, which significantly modifies the
amount of
absorption of the x-wave. Because of this, the x-wave is usually ignored in
propagation
studies on 160m (and on the AM broadcast band, too). This effect is also
seen on 80m,
but to a lesser extent."
http://mysite.verizon.net/k9la/sitebuildercontent/sitebuilderfiles/polarization.pdf
Several who have tried *high* horizontal dipoles (0.5 wl = 270') on 160 find
they do not work nearly as well as verticals. Conversely, on 80 meters,
horizontal antennas work very well indeed. I'm sure the 5 element at the
OH8X site will work quite well, but the jury is still out on the 160 Yagi
IMHO. I hope they have a good vertical system for comparisons.
If you want to read (a lot!) more, try typing "coupling loss" or
"polarization loss" into the box at the top of this page:
http://lists.contesting.com/archives//html/Topband/
73, Bill W4ZV
--
View this message in context:
http://n2.nabble.com/OT%3A-3L-rotating-160m-yagi-tp2093095p2095850.html
Sent from the Elecraft mailing list archive at Nabble.com.
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