When you are holidaying down at the beach, you often see two wavetrains,
possibly from the incoming tide and a rip tide reflected from rocks,
crossing
each other.

One result is that depending upon the relative phases, that the peaks and
troughs can be
twice as large as normal, but, once the two wave trains have passed each
other, they
continue on individually as though no interaction had taken place.

This, ISTR, is down to the superposition principle.

Now, here comes the quandary, why is it that when feeding energy into a
feeder that
the impedance encountered depends on what has been reflected from the
antenna?
Surely, by the analogy of the beach waves, the incident and reflected waves
should
only see the impedance of the feeder, with each being superimposed on the
other?

"gareth" wrote in message
...
When you are holidaying down at the beach, you often see two wavetrains,
possibly from the incoming tide and a rip tide reflected from rocks,
crossing
each other.

One result is that depending upon the relative phases, that the peaks and
troughs can be
twice as large as normal, but, once the two wave trains have passed each
other, they
continue on individually as though no interaction had taken place.

This, ISTR, is down to the superposition principle.

Now, here comes the quandary, why is it that when feeding energy into a
feeder that
the impedance encountered depends on what has been reflected from the
antenna?
Surely, by the analogy of the beach waves, the incident and reflected
waves should
only see the impedance of the feeder, with each being superimposed on the
other?

PS. When doing a Thevenin analysis with more than one voltage source
present in a network, you analyse the response to one voltage source as
though
no other EMF is present (Yes, replace by their source impedances)