[TowerTalk] Takeoff Angles and Non-Reciprocal Propagation

[Rick Karlquist]

David Gilbert wrote:

> I've read the pdf file written by N6BV that accompanies HFTA several

> "It is fascinating to reflect on the thought that received signals
> coming down from the ionosphere to the receiver are having encounters
> with the terrain, but from the opposite direction.  It is not
> surprising, given these kinds of interactions, that transmitting and
> receiving might not be totally reciprocal."
>
> It occurs to me that there might be a way to see if this actually
> happens.  A station in the U.S. could pair up with a station in Europe

We need to distinguish between reciprocity of diffraction vs
reciprocity of ionospheric processes.  A much easier way to
demonstrate the reciprocity of diffraction would be to connect
microwave horn antennas to a network analyzer and measure S12
and S21 in real time.  You could insert whatever objects you
wanted between the horns in an effort to cause a difference between
S12 and S21.

Note that if the ionosphere is non-reciprocal, it will be so
regardless of any terrestrial diffraction effects.

Rick N6RK