wrote:
W5DXP wrote:
I forgot to add. At the "zero-power points", either voltage or current is
zero. All that means is that all the energy is contained in the opposite
field.

Not quite all. It also means that there is NO power since P = V x I.

It means there is no NET power transfer. There are power flow vectors
in both directions that are equal in magnitude. Reference: _Fields_
and_Waves_in_Communications_Electronics_ by Ramo, Whinnery, & Van Duzer,
section 6.10, page 350, where they describe Pz-, the reflected wave
Poynting vector and Pz+, the forward wave Poynting vector.

There can be lots of energy present but none of it is flowing past
the zero voltage or zero current point; hence no power.

There is a forward power flow vector and a reflected power flow vector.
There is no net power flowing past any point. There are, however, equal
magnitude component constant power flow vectors flowing in both directions.

To believe that energy is flowing across a zero voltage or zero current
point requires the rejection of the view that instantaneous power is
equal to instantaneous voltage multiplied by instantaneous current.

No, it doesn't. It only requires acceptance of Ramo, Whinnery, & Van Duzer.

However, to reject energy flow across a zero voltage or zero current
point requires a confusion of cause and effect. Energy flow in both
directions is the *CAUSE* of the standing waves. You simply cannot
turn around and say that standing waves eliminate their own cause
but continue to exist anyway.

Rejection of
P = V x I would have wide impacts on our understanding of electrical
power and energy flows.

Nobody is rejecting it. If the lossless stub is one second long, it takes
two seconds of *POWER* to bring it to steady-state. If the stub contains
no moving energy, where did all those joules go? They cannot disappear or
stand still. If they are moving, power exists.
--
73, Cecil http://www.qsl.net/w5dxp



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