Topband
[Top] [All Lists]

Re: Topband: 160m polarization and elevation angles

To: Carl Luetzelschwab <carlluetzelschwab@gmail.com>
Subject: Re: Topband: 160m polarization and elevation angles
From: Mark K3MSB <mark.k3msb@gmail.com>
Date: Thu, 29 Mar 2018 18:20:11 -0400
List-post: <mailto:topband@contesting.com>
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
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
_________________
Topband Reflector Archives - http://www.contesting.com/_topband

<Prev in Thread] Current Thread [Next in Thread>