Roy Lewallen wrote:
Roger wrote:

By storage factor, I simply mean the ratio of
forward power to total power on the transmission media under standing
wave conditions.


Power is neither stored nor conserved, so a power "storage factor" is
meaningless. Consider a very simple example. Let's charge a capacitor
with a constant current DC source. We'll apply 1 amp to a 1 farad
capacitor for 1 second. During that time, the power begins at zero,
since the capacitor voltage is zero, then it rises linearly to one watt
as the capacitor voltage rises to one volt at the end of the one second
period. So the average power over that period was 1/2 watt, and we put
1/2 joule of energy into the capacitor. (To confirm, the energy in a
capacitor is 1/2 * C * V^2 = 1/2 joule.) Was power "put into" or stored
in the capacitor?

Now we'll connect a 0.1 amp constant current load to the capacitor, in a
direction that discharges it. We can use an ideal current source for
this. The power measured at the capacitor or source terminals begins at
0.1 watt and drops linearly to zero as the capacitor discharges. The
average is 0.05 watt. Why are we getting less power out than we put in?

"Where did the power go?" is heard over and over, and let me assure you,
anyone taking care with his mathematics and logic is going to spend a
long time looking for it. So in this capacitor problem, where did the
power go?

It takes 10 seconds to discharge the capacitor, during which the load
receives the 1/2 joule of energy stored in the capacitor. Energy was
stored. Energy was conserved. Power was neither stored nor conserved.

Roy Lewallen, W7EL

By my using the words 'power' "storage factor", you got my point, hence
the reaction.

Before dismissing the concept of "storing power", consider that when
discussing a transmission line, it could be a useful description.

As you know, power is energy delivered over a time period. It always
carries a time dimension having beginning and end. Power(watt)
=v*i/(unit time) = 1 joule/second.

In the example you give of charging a capacitor, the time dimension is
lost, so you are correct that only energy is conserved. Power is lost.

With a transmission line, we have an entirely different case. Here
power is conserved because the time information is maintained. Power is
stored on the line during the period it resides on the line. For
example, we excite the line at one end and some time period later find
that power is delivered to some destination. During the time period
that the power was on the line, the information that defines the energy
distribution over time has been preserved.

If power is stored, we implicitly store energy. Energy is v*i measured
in joules without a time factor. Obviously we store energy on a
transmission line when we store power.

So if in the future, I use the term "power storage", please take it to
mean that energy distributed over time is under consideration. I hope
the term might be useful to you as well.

73, Roger, W7WKB