On Jul 1, 8:37*am, Cecil Moore wrote:
On Jun 30, 11:29*am, Keith Dysart wrote:

Check the a0 coefficient in the Fourier transform. This represents
the DC component of the signal.

And the result is zero EM waves, either forward or reflected, and your
argument falls apart.

What was my argument that fell apart? I am not the one pushing the
notion
of forward and reflected EM waves. That's you. I am just trying to
help
you fit square waves in to your model.

So how do you characterize a slow square wave? Say one that is 0V for
one year, then 10V for a year, then 0, then...

With several meters of open circuited transmission line, what do you
think is happening on the line for the year while you are waiting for
the
signal to drop back to zero volts? Does it have a constant voltage?
And
0 current for most of that year? Is it an EM wave?

Without this, how would you deal with a signal such as
* V(t) = 10 + 2 cos(3t)

If the cosine term is zero, there are zero EM waves, either forward or
reflected, and your argument falls apart.

Incidentally, V(t) = 10, is a perfect way to prove that energy and the
time derivitive of energy are not the same thing and your argument
falls apart.

You need to read more carefully. I have never claimed they are the
same.

Alternatively, one can use the standard trick for dealing with
non-repetitive waveforms: choose an arbitrary period. 24 hours
would probably be suitable for these examples and transform from
there. Still, you will have zero frequency component to deal
with, but there will be some at higher frequencies (if you
choose your function to make it so).

Windowing doesn't generate EM waves where none exist in reality and
your argument falls apart.

A question for your model...

With an infinitely long transmission line excited by a step function,
is there an EM wave propagating down the line?

If not, what is it that is propagating down the line? Especially at
the leading edge?

....Keith