On Sun, 6 Jun 2010 11:01:20 -0700 (PDT), K1TTT wrote:

as in the other thread, what is the mechanism of that 'interaction'
between waves? i contend there can be no 'interaction' between
forward and reflected waves if the device is linear. so in an ideal
case of a voltage or current source and ideal source resistance there
is no interaction, it is reflected by and/or absorbed in the source
depending on the impedance of the line and source.

There is no mixing as in multiplication of waveforms. Perhaps I can
offer a simple analogy. Instead of two AC waveforms (forward and
reflected), use a DC equivalent. Start with two DIFFERENT batteries.
Connect the two negative ends together and declare that to be ground.
Connect a resistor between the positive terminals. The two voltages
most certainly "interact" across the resistor, resulting in the
current and power being proportional to the difference between the two
battery voltages. Nothing in this crude example is non-linear, so
there's no need for mixing in order to get interaction.

Similarly, the coax cable acts much in the same way. The two
batteries are replaced by the incident and reflected signals. At any
time, or position on the transmission line, the model can be frozen
and the instantaneous voltages and currents be calculated.

if the source is
not linear then you would have to calculate the effect of the sum of
the voltages or currents at the source to determine the effect.

If the source (or load) is non-linear, then the waveforms seen on the
transmission line will be distorted. This is unlikely because we
usually don't install diodes in antennas, or build HF amplifiers with
substantial non-linearities (i.e. distortion).



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558