Roy Lewallen wrote in news:132fvs4qvp5je04
@corp.supernews.com:

I believe there's at least one basic fallacy in your development.

The problem is that a directional antenna can't be made to take up zero
space. Let's consider a situation where we can have complete

Roy, the type of probe I was considering does take up space, and I
understand your point that therein lies a possible / likely explanation
for its behaviour.

I was thinking along the lines of the superposition occuring within the
directional antenna where segment currents would each be dependent on the
field from each of the sources (and to some extent field from other
segments of itself), and the antenna was where the superposition mainly
occurred. But you are correct that the antenna is of non zero size, and
the segments that I refer to are not all located at a point where the
field strength from each source is equal and opposite.

....

I maintain that there is actually zero field at a point of
superposition
of multiple waves which sum to zero, and that no device or detector can
be devised which, looking only at that point, can tell that the zero
field is a result of multiple waves. This is a very important and
fundamental point, and I'm glad you brought it up. If you or anyone can

I understand the second point.

Extended to transmission lines, I think it means that although we can
make an observation at a single point of V and I, and knowing Zo we can
state whether there are standing waves or not, we cannot tell if that is
the result of more than two travelling waves (unless you take the view
that there is only one wave travelling in each direction, the resultant
of interactions at the ends of the line).

I will think some more about the "actual zero field", but that cannot
suggest that one wave modified the other, they must both pass beyond that
point, each unchanged, mustn't they? If that is so, the waves must be
independent, but the resultant at a point is something separate to each
of the components and doesn't of itself alter the propagation of either
wave.

Owen