Constructive interference in radiowave propagation
"Keith Dysart" wrote in
ups.com:
....
Just another reason why you have to be careful when you think
that the forward and reverse waves necessarily represent real
power. Trust the power folk on this one; they know what represents
Keith, that was indeed my point, that talking of the forward and
reflected waves as power waves (or whatever non-phasor term is being used
today) and the assertion that those "power" waves are entirely real power
(for whatever reasons), and the talk of superposition of these waves
(where the examples seem to deal with power algebraicly with sometimes a
fudge for phase correction) cannot explain the role of a transmission
line as an energy store at any instant, nor the exchange of reactive
energy at source and load over time.
If that seems a jumble, it is because this stuff is bandied around
without much discipline.
In the same vein, I saw an assertion without sufficient qualification
that in a transmission line, 50% of the energy is stored / contained in
the electric field and 50% in the magnetic field. Again, general
statements from specific cases.
It isn't the special case of a lossless line the causes this, it is the
conclusions that are incorrectly drawn from the lossless line or
incorrectly applied that are the problem.
Owen
|