Yes, on some of the bands circular polarization is used for EME
On Wed, Feb 12, 2014 at 12:47 PM, Charlie Cunningham < [email protected]> wrote: > BTW - does anyone know if the EME boys employ circular polarization? > > 73, > Charlie, K4OTV > > -----Original Message----- > From: Topband [mailto:[email protected]] On Behalf Of > Charlie Cunningham > Sent: Wednesday, February 12, 2014 1:35 PM > To: 'Tom W8JI'; [email protected]; [email protected] > 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:[email protected]] On Behalf Of Bill > and Liz > Sent: Sunday, February 02, 2014 8:37 PM > To: [email protected] > 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:[email protected]] On Behalf Of Tom > W8JI > Sent: Wednesday, February 12, 2014 10:41 AM > To: [email protected]; [email protected] > 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: <[email protected]> > To: <[email protected]> > 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:[email protected]] > >> Sent: > > Wednesday, February 05, 2014 10:45 PM > >> To: [email protected]; 'Tom > > W8JI'; [email protected]; > >> [email protected] > >> 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 > >> > >> > > _________________ > >> Topband Reflector Archives - > > http://www.contesting.com/_topband [2] > > > > > > Links: > > ------ > > [1] > > http://k9la.us/html/160m.html > > [2] http://www.contesting.com/_topband > > _________________ > > Topband Reflector Archives - http://www.contesting.com/_topband > > > > ----- > > No virus found in this message. > > Checked by AVG - www.avg.com > > Version: 2014.0.4259 / Virus Database: 3697/7085 - Release Date: 02/11/14 > > > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband -- 73 Joel W5ZN www.w5zn.org _________________ Topband Reflector Archives - http://www.contesting.com/_topband
