WIll add my two cents to this discussion.
One thing I have experience with is diversity reception both on 160 and 80
meters. Often - I would be using my TX antenna in one ear and a beverage
in another. On 80 meters, the TX antenna was a 4 square. On 160, either a
vertical or two element phased array.
I found on 80 meters - when running JAs in a contest - if I only used one
antenna - I would almost always miss one letter of the JA's callsign and
have to ask for a repeat... but with diversity - the signal would float
around in my head and I could almost always get the whole call the first
time.
I can hear this effect on 160 as well as signals float around. I can't
prove this is just polarization - as it could be different angles of signal
arrival - but it sure re-enforces the point that having different kinds of
RX antennas for different situations is never a bad thing.
I have experienced some sunrise openings where a low dipole has worked
well. There are times when my directive receive antennas seem to be broken
- which is another indication of high angles.
Tree N6TR
On Wed, Nov 28, 2018 at 8:51 AM Yuri Blanarovich <k3bu@optimum.net> wrote:
> Not knowing about "gyros", but when operating and having vertical and
> horizontal antennas available, I remember times when QSB was happening
> on one antenna, switching to the "other" polarization antenna would
> bring the signals up.
> My conclusion was that at the times the signal's polarization was
> rolling around, especially when far DX.
>
> Yuri, K3BU, VE3BMV, VE1BY
>
>
> On Wed, Nov 28, 2018 at 09:22 AM, Robert Parkes via Topband wrote:
>
> >
> > Polarization on 160m
> >
> > Interesting discussion and one I suspect we wish could fully
> > comprehend !
> >
> > When the wave front meets the ionosphere and the wave splits the
> > critical frequency is different for the two waves, commonly known as
> > foc and fxc.
> > This difference (from memory) is half the gyrofrequency and can often
> > be seen on Ionosonde plots with two sets of reflections. The gyro
> > frequency depends on the strength of the magnetic field at that point
> > of the ionosphere so can vary from 700kHz to 1.4MHz where the radiated
> > wave interacts with the Ionosphere Layer be it, E layer or F layer.
> >
> > Being radio amateurs and pushing the envelope we are trying to make
> > that illusive QSO so we need to excite a propagation path which is
> > normally at the limit in order to chase the DX.
> > Assuming conditions are favourable, and if the angle of arrival and
> > critical frequency is such that it favours both wave fronts then for a
> > single and multi-hop transmission both the O-wave and the X-wave will
> > be propagated.
> >
> > The higher frequency of the two wave fronts, the X-wave may propagate
> > which could result in a QSO whilst those around us may not have quite
> > the same favourable conditions and only the O-wave is propagated on a
> > differeing path while the X-Wavecould fall by the wayside and not be
> > propagated.
> > One result of all this variability could result in what has been
> > called spotlight or torchlight propagation. I recall Eric K3NA giving
> > a talk along these lines when referring to 3B7C 160m operations and
> > how that spotlight moved across North America during the course of his
> > opening to the US.
> > There is a possibility that Circular Polarisation would assist
> > with both the O and X wave modes of propagation and it could be argued
> > that a "compromise" Inv-L antenna provides this with its Vertical and
> > Horizontal elements making up the antenna and resulting mixed
> > polarisation.After all a number of amateurs have had good success with
> > an Inv-L.
> >
> > 73sBob ParkesG3REP(ex - S21YP, 4S7RPG, A45XF, VS5RP, P29PR)
> > _________________
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> > Reflector
> >
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