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/0B8I6Nck0GwTdYTI0MzVkY2QtYjUyYS00YmE3LTk4NTktNWVlNzE2ZGFiYmE1/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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