On 2005-02-16, Buck wrote:

We know the ionosphere affects propagation. It is assumed that
signals take the same path and therefore should have the same
strength, but I don't think so. If the ionosphere is dense (relative
to my frequency) behind and over my station, I may be using it as a
'dish' reflector. However, at your location, you may have a porous
ionosphere so rather than your signal being reflected, it is being
absorbed. The result is that I have an ERP of 200 watts and you reply
to me with an ERP of 20.

takeoff angle also plays a big part in this. One station may have a lower
angle and be making only 1 hop to the other station, while the other station
may have a higher angle and be hitting the first station via 2 hops --
resulting in some signal loss.

--
Alex / AB2RC
Linux is user friendly, however it is not idiot friendly