Thanks, Joel! That makes perfect sense to me! I don’t keep up with EME, as
I’m an HF CW DXer, but it seemed that the EME guys might use circular
polarization to contend with the Faraday Rotation in Earth’s atmosphere,
from my spacecraft days of long ago! Thanks!
73,
Charlie, K4OTV
From: Joel Harrison [mailto:w5zn@w5zn.org]
Sent: Wednesday, February 12, 2014 2:14 PM
To: Charlie Cunningham
Cc: Tom W8JI; dado@prijedor.com; topband@contesting.com
Subject: Re: Topband: circular polarization on 160m -BTW
Yes, on some of the bands circular polarization is used for EME
On Wed, Feb 12, 2014 at 12:47 PM, Charlie Cunningham
<charlie-cunningham@nc.rr.com> wrote:
BTW - does anyone know if the EME boys employ circular polarization?
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Charlie
Cunningham
Sent: Wednesday, February 12, 2014 1:35 PM
To: 'Tom W8JI'; dado@prijedor.com; topband@contesting.com
Subject: Re: Topband: circular polarization on 160m
Hello all,
My original post regarding circular polarization receiving antennas for
160
was posted 2/2/2014 as a comment on Bill, VE3CSK's post regarding his
observation of apparent rapid polarization shifts in the signal received
from FT5ZM, on Amsteram Island at their sunrise. Bill was using his K3 in
diversity mode to observe the apparent rapid polarization shifts by using
both vertical and horizontal receive antennas. The rapid apparent
polarization shifts seemed quite different from the slower QSB that we
often
experience on 160. I post my original hurried off-hand comment and Bill's
post below;
"I wonder what circular-polarized RX antennas might have to offer on 160?
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Bill
and
Liz
Sent: Sunday, February 02, 2014 8:37 PM
To: topband@contesting.com
Subject: Topband: FT5ZM SIGNAL
I have been listening several evenings now on 160M using my K3 in
diversity
mode with the TX vertical array on one receiver and a full-wave horizontal
loop on the other. I have been struck by the often rapid change in the
signal as received on one antenna or the other. As sunrise on Amsterdam
approaches this shift becomes quite rapid, with the recovered signal
bouncing back and forth ear to ear. Early on, before I began listening in
diversity mode, I thought it was rapid QSB taking the signal down into the
noise but now realize that it is the angle of the arriving signal which is
rapidly changing over the path.
No wonder some of the guys have been having problems copying/working the
expedition on topband!
Bill VE3CSK"
This seemed to provoke an interesting, lively and informative discussion
by
a number of people who have explored 160m ionosphere propagation in far
greater depth than I have. Some of the commentary piqued my interest and
caused me to want to do some more research! Thanks guys, and thanks, Tom,
for your recent postings of your recordings from KH6AT etc.! Rather
informative and thought-provoking!
I must confess that all of my experience with circular polarization has
been
at UHF (400 MHz range) for spacecraft telemetry and 1.4 GHz for GPS
signals. In these cases circular polarization is employed to contend with
the Faraday Rotation of signals as they propagate through Earth's
atmosphere. These signals generally originate beyond the ionosphere except
for a few birds that might pass through the "magneto-tail" on the lee-side
(dark-side) of earth away from the solar wind. Very different from 160m
signals that originate on Earth's surface and are reflected from an
ionization layer in the ionosphere!
Bill's observations are really interesting and seem to suggest something
other than the usual slow fades that we are used to on topband. Surely
piqued my curiosity!
I would think that with proper phase control one could construct circular
polarized 160m receive antennas that could be less than full-size if
preamps
were employed. It's interesting to consider that such an antenna would
probably be RHCP in one direction and LHCP in the opposite direction! If I
wasn't so disabled at present, I' be tempted to build something to
experiment with, just because I miss building experimenting with and
measuring antennas! Very enjoyable
activities for me!
Anyway, thanks all for all the commentary and insightful and
thought-provoking discussions! Bill's observations seem to suggest
something different at work that may deserve some further investigation
and
exploration! That led me to wondering about circular polarization, or
perhaps some rapid high-speed commutation between horizontally polarized
and
vertically polarized receive antennas. Thanks!
73,
Charlie, K4OTV
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Tom
W8JI
Sent: Wednesday, February 12, 2014 10:41 AM
To: dado@prijedor.com; topband@contesting.com
Subject: Re: Topband: circular polarization on 160m
Here are some pictures and a sound file or two...
http://www.w8ji.com/HF%20circular%20polarization.htm
----- Original Message -----
From: <dado@prijedor.com>
To: <topband@contesting.com>
Sent: Wednesday, February 12, 2014 6:41 AM
Subject: Re: Topband: circular polarization on 160m
hi Guys,
interesting discussion
If want, hear this file,
https://drive.google.com/file/d/0B8I6Nck0GwTdYTI0MzVkY2QtYjUyYS00YmE3LTk4NTk
tNWVlNzE2ZGFiYmE1/edit?usp=sharing
this is E74AW and OZ1LXJ recording of ZL3IX, at same time, John was
so kind and sinchronise those two audio recordings together in one file,
will hear how QSB is different on different station, when peak is on
my side, deep gos to John and VV
thanks, 73 cul dado E74AW
Дана
06.02.2014 06:21, James Wolf је написао:
Jose,
I am only
presenting the possibility that if the ionosphere (where 160
propagation happens) isn't uniformly smooth and instead consists of
"warps,
wrinkles and tilts" that in a *dynamic ionosphere*, this could
be at least
one reason we are experiencing slow fades.
Elliptical
polarization, assuming that it is ever changing, could provide
yet
another degree of selective fading.
I'm don't think I *totally*
understand why KL7AJ says that "at HF the
ionosphere forbids the
propagation of linearly polarized signals". If at
the magnetic
equator, and signals were East to West to equal the earth
magnetic
tilt of the signals, it seems that at an instance in time that a
linear polarized signal could happen. But that may be nit picking.
Jim - KR9U
From: JC N4IS [mailto:n4is@comcast.net]
Sent:
Wednesday, February 05, 2014 10:45 PM
To: jbwolf@comcast.net; 'Tom
W8JI'; herbs@vitelcom.net;
topband@contesting.com
Subject: RE:
Topband: circular polarization on 160m
James
You brought a
good article about HF propagation, however the behavor on 160m
is
different from HF. If you check on the KL7A arcticle figure 1 what is
happening between 1 and 2 MHz you can see that the green and red does
not
behaivor the same way as above 2 MHz.
This subject is more
complex because there us no shirt answer, actualy
between 1 and 2 MHz.
the ionosphere does not support linear polariration
wave. The wave are
actualy eliptical and not circular for most directions.
You can
check the long answer on the "must read book" from NM7M . R Brown
'The
Big Gun's Guied to Low Band Propagation" . Magneto-iomic Theory pag 47
to 56 ; and Power coupling pag 57.
Thanks to Karl. K9LA, the book
is available on his also must read site on
the 160m link
http://k9la.us/html/160m.html [1]
Regards
JC
N4IS
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Links:
------
[1]
http://k9la.us/html/160m.html
[2] http://www.contesting.com/_topband
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73 Joel W5ZN
www.w5zn.org
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