J. Mc Laughlin wrote:
I too am reluctant to enter this as much resembles a freshman poli-sci
student debating a third year law student.

However .... please see indented comments below

. . .

Here I must inject my experience. As part of a topic sentence, "tends to be
the same" is OK. However, it is common on real HF paths of over 4 or 5 Mm
for the elevation angle at which the strongest signal arrives to be
significantly different at the two ends of the path. It is easy on longer
paths for the major mode at one end to be using a high virtual-height F2
mode and for the other end to be using a low virtual-height E mode.

Allow me to put to rest the notion that optimum elevation angles are
necessarily the same at both ends of a longer (multiple hop) HF path! [Reg
did not say that optimum elevation angle are necessarily the same.]

. . .

I'm glad you did get yourself to contribute to the discussion. I'm by no
means an expert when it comes to propagation (and quite apparently
several other participants aren't either), and I've fallen victim to
using oversimplified models where their use isn't appropriate. The
little reading I've done on the topic shows there are some really
interesting phenomena involved which don't at all fit with the notion of
simple reflection or refraction from a layer at a single height. Thanks
for reminding us about one of the more important ways in which the
simplified models are misleading.

As other have said, but not all have heard, the idea is to maximize gain
(at both ends of a path) at the elevation angle being used. Even in the
20s, antenna systems were in regular use that attempted to do just this.

. . .

Even if it were possible to do so, one would not use an antenna that had all
of its gain at the predicted optimum elevation angle. One would try to
design an antenna (money enters here) that has most of its gain in the
expected band of elevation angles expected to be best for a path.


Agreed.

Roy Lewallen, W7EL