k3bu@optonline.net wrote:
> Let me just throw another aspect - the polarization twist. When signals
> are transmitted with one polarization and arrive at different. If the
> media is so linear, how could that happen? How do you "prove" that effect
> with laser or flashlight and perfect mirrors?
Polarization and linearity are independent of each other.
A medium can rotate polarization or not whether it is linear or not.
The issue is not linearity but rather reciprocity. In reciprocal
media, the twist imparted to a signal going in a given direction
is the opposite of the twist imparted to a signal going in the
opposite direction. This never results in one way propagation.
In any event, the ionosphere is linear, at least at amateur power
levels.
Non reciprocal media can impart the same twist to signals going
in opposite directions. (Example Faraday rotator). This can
result in one way propagation. I don't know if the ionosphere
can be non-reciprocal, but it might be possible since there are charged
particles in magnetic fields. However, there is no non-reciprocal
mechanism for any terrestrial propagation modes propagating
in air (eg diffraction).
Rick N6RK
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