On Jan 3, 11:01*am, Mike Monett wrote:
* Keith Dysart wrote:

* On Jan 3, 1:07am, Mike Monett wrote:

* Keith, your *model is not realistic. As you know, any *signal you
* impose on a conductor will form an electromagnetic wave. *This is
* the combination of electrostatic and electromagnetic *fields, and
* it propagates at the normal velocity for that medium.

* However, electromagnetic *waves do not interact with *each other,
* and they cannot bounce off each other.

* That is *the *standard *description, but *it *seems *to *have some
* weaknesses.

* No, there are no weaknesses. Maxwell's equations have stood the test
* of time.

* Recall that light from stars is electromagnetic. It tra vels many
* light-years before it reaches your eyes. If electromagnetic waves
* interacted, you *would not be able to see *individual *stars they
* would merge into a blur.

* This would seem to me to depend on the nature of *the interaction.
* Clearly the interaction represented by the term "bounce" (for lack
* of a *better word) would have to be such as to not violate *any of
* these observed behaviours.

* The term *"bounce" means they interact. *Electromagnetic *signals do
* not interact. *They *superimpose. *Each *is *completely *unaware and
* unaffected by the other.

* Similarly, the *signals reaching your antenna and *traveling down
* the coax *to *your receiver do not interact with *each *other. As
* long as *your receiver is not overloaded, the signals *remain sep
* arate no matter how many stations are on the air at the moment.

* So the *statement *that *like charges *repel *does *not *apply to
* electromagnetic waves,

* Q1. Are you saying that it is inappropriate to view a transmission
* line as *distributed *capacitance and inductance *and *analyze its
* behaviour using charge stored in the capacitance and moving in the
* inducatance?

* That is *not *what *you are saying. You *are *ignoring *the magnetic
* field.

* If such analysis is appropriate, then it seems to me that *a pulse
* can be viewed as a chunk of charge moving down the line.

* Q2. Is this an appropriate view?

* No. You need to include the associated magnetic field.

* Q3. If *so, *then *what happens when *two *such *chunks *of charge
* collide in the middle of the line?

* Electromagnetic signals do not collide. They superimpose.

* The existing *analysis *techniques tell us *that *no *current ever
* flows at *the mid-point of the line, this means no *charge crosses
* the mid-point.

* Q4. Is this correct?

* That statement has no meaning.

* Q5. If *no charge crosses the mid-point, then how *do *the pulses,
* made up of chunks of charge. pass the mid-point?

* The pulses *are *not chunks of charge. They are *the *combination of
* electrostatic and *electromagnetic fields. You *cannot *separate the
* two.

* Q6. If they do not pass the mid-point, then what happens to them?

* That statement has no meaning.

* I have offerred a somewhat intuitive explanation.

* Your explanation does not work.

* Other explanations are welcome.

* Any explanation *that *does not *involve *charge *will immediately
* cause me to ask Q1 again.

* Please study Maxwell's equations and how they are derived.

* Keith

* Regards,

* Mike Monett

You did not directly answer Q1, but I take if from all
the other responses that you are saying the answer is
"no, it is not appropriate to view a transmission
line as distributed capacitance and inductance and
analyze its behaviour using charge stored in the
capacitance and moving in the inducatance?"

Taking this invalidates all the subsequent questions
since they are based on the premise that this kind
of analysis is appropriate.

Or have I misinterpreted and your only concern with
Q1 was that I did not mention that energy is stored
in the electric field created by charge in the
capacitance and the magnetic created by charge
flowing in the inductance?

...Keith