Carl
I learned that polarization is not predictable after the first ionospheric
bounce.
73 Mark K3MSB
On Thu, Mar 29, 2018 at 1:30 PM, Carl Luetzelschwab <
carlluetzelschwab@gmail.com> wrote:
> Polarization - As Jerry K4SAV stated, the electron gyro-frequency plays an
> important role on 160m since our ionosphere is immersed in a magnetic field
> - it also affects ionospheric absorption and refraction. For those of us at
> mid to high latitudes, vertical polarization on 160m is *theoretically*
> optimum since it couples the most energy to the limiting polarization at
> the entrance to the ionosphere. I don't understand Mark K3MSB's comment
> about the polarization terms disappearing unless it has to do with that
> fact that the polarization going up to the ionosphere has nothing to do
> with the polarization going thru the ionosphere (which is dictated by the
> ionosphere).
>
> Elevation angles - Ray tracing shows that elevation angles up to about 10
> degrees are E hops since there is still enough E region ionization at night
> to refract 160m. I don't know how important these E hops are - probably
> okay for short distance, but the losses (absorption and ground reflection)
> add up quickly for the longer distances. Above 15 degrees or so we get F
> hops. From 10-15 degrees is where ducting occurs in the electron density
> valley above the nighttime E region. Ducting in the valley likely requires
> shallow angles. But when a signal gets dumped out of the duct, that
> suggests a higher down-coming angle.
>
> K4SAV said it best: ". . . and the real world on 160 is very complicated."
>
> Carl K9LA
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