Cecil Moore wrote:
Owen Duffy wrote:
"AI4QJ" wrote:
not so nicely linear. The antenna is a lossy transmission line just as
Owen's example was a lossy xmission line example with a 25 ohm load at

No, my example stipulated an ideal transmission line, and by that I
mean it to be lossless amongst other things.

What we are saying is that even if the transmission line
is lossless, the *system* is lossy because of the 25 ohm
resistor.

If there were no losses in the *system*, the waves on the
lossless transmission line would be pure standing waves.
Because of the losses in the load, the waves on the lossless
transmission line are not pure standing waves, but a mixture
of standing waves and traveling waves. In your case (#1 below)
the system is primarily a traveling wave system, closer to
flat than to an OC or SC stub because only 11% of the forward
energy is rejected by the load.

You and Cecil are transforming the example to suit yourselves.

I'm not transforming the example. You are the one who put
the lossy resistor in the system. The traveling waves are
the direct result of the installation of the resistor.

Let's look at a few different examples and assume the
measured joules/sec flowing forward toward the load is
100 joules/sec in each case.

1. Your example of 50 ohm lossless coax connected to a 25
ohm load. The forward joules/sec is 100. The reflected
joules/sec is 11.11. The joules/sec consumed by the 25
ohm load is 88.89. 89% of the forward wave is traveling
wave. 11.11% of the forward wave is used by the standing
wave. The system is primarily a traveling wave system.
The energy not delivered to the load is stored in the
standing wave in the LCLCLCLC components of the
transmission line.

2. No load on the lossless coax. The forward joules/sec
and the reflected joules/sec are equal. 100% of the energy
is standing wave energy and all of it is stored in the
LCLCLCLC components of the transmission line. It does not
move from LC to LC. It simply oscillates in place between
L and C. EZNEC confirms that the current phasor does NOT
rotate.

3. 50 ohm load on the lossless coax. The reflected joules/sec
equals zero and the system is flat. 100% of the energy is
traveling wave energy. The only energy in the transmission
line is the energy it took to fill the pipeline, the delay
between power-on and the load dissipating power. The LCLCLCLC
in this case is an energy bucket brigade.

4. 500 ohm load on the lossless coax. Of the forward 100
joules/sec, only 33 joules/sec is accepted by the load.
The other 67 joules/sec are rejected by the load and become
half of the energy in the standing wave. The system is
primarily a standing wave system. The energy not delivered
to the load is stored in the standing wave in the LCLCLCLC
components of the transmission line.
Cecil, I think this is an excellent series of examples, and greatly
helps me understand your thinking. Roy also wrote a great posting,
which I will respond to shortly.

But I wonder if you are thinking of the standing wave as the end of the
reflected wave, or as the envelope described by the reflected waves as
they sequence in time. These choices at first sound nearly identical,
but they are not. A sequence of reflected waves results in sequential
changes that affect the input power. The final standing wave will not
be defined until several sequential waves have occurred. Unless
adjusted, the ongoing stable power flow to the load will be reduced (or
increased) from the initial value by the effects of the standing wave.
So think I.

Thanks for this series of examples.

73, Roger, W7WKB