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Old April 14th 08, 09:57 PM posted to rec.radio.amateur.antenna
Keith Dysart[_2_] Keith Dysart[_2_] is offline
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First recorded activity by RadioBanter: May 2007
Posts: 492
Default The Rest of the Story

On Apr 14, 1:36*pm, Cecil Moore wrote:
Keith Dysart wrote:
Ahhh, but there is then agreement that energy flows (power) must
be in balance to satisfy conservation of energy.


You can probably answer your own question by figuring
out how the light energy in an interference pattern
gets from the dark ring to the bright ring some
distance away. Do you think it happens faster than
the speed of light?


What is your explanation for this phenomenon?

It is just that it comes up short since there is no
explanation of where the energy goes. Were an adequate
explanation to be offered, I would quite accept it.


I am satisfied with the destructive/constructive
interference explanation. That you have come up
short in tracking those component energies is not
unexpected given your prejudices.


I suppose. If you are happy with energy equations that
don't balance.

If you told me your car disappeared from existence
because you cannot find it, I wouldn't believe you
either.

You should tread back through the posts, the question was
answered.


"It depends" was no answer - that was just mealy-mouthing.


Except, that it does depend.

In the special case presented in Part 1, there are only
two sources of power dissipation in the entire system,
the load resistor and the source resistor.


Three! The source can also take energy from the system.


The Vs source has zero resistance rendering dissipation
impossible. I repeat: There are only two sources of
power *DISSIPATION* in the entire system, the load
resistor and the source resistor.


You have to read more carefully. I did not use the word
dissipation. This is because there are ways other than
dissipation to remove energy from the system. Just as
the source provides energy and we do not care where it
comes from, it can remove energy and we do not care where
it goes.

Examine Ps(t). You will find that for some of the time
energy is being absorbed by the source. This occurs
when the sign of Ps(t) is negative.

The source can certainly throttle back its output when
there is destructive interference in the source resistor
and increase its output when there is constructive
interference in the source resistor, but it CANNOT
dissipate any power.


Since we don't know the internals of the source, we do not
know if it is dissipating or not. But we do know that when
the sign of Ps(t) is negative, the source is absorbing
energy from the system, exactly analagous to it providing
energy when the sign of Ps(t) is positive.

Since you have overlooked the source, the rest of your
post is quite flawed in its conclusions.


Nope, you are confused. The source can adjust its output
but the source cannot *DISSIPATE* power. As I said, the
only sources of power *DISSIPATION* are the two resistors.
No amount of obfuscation is going to change that.


You really should rethink this a bit. When current flows into
a voltage source, the voltage source is absorbing energy.

Perhaps adding a circulator to my Part 1, Fig. 1-1 will
allow you to see things in a clearer light. Of course,
using light would be even better.

Gnd--1---2---Vs---Rs-----45 deg 50 ohm----------RL
* * * *\ /
* * * * 3
* * * * |
* * *50 ohms
* * * * |
* * * *GND

How much power is dissipated in the circulator
resistor?


This circulator, while often used, does not in any way add
clarity.

Changing the circuit changes the results, especially when
you add a circulator which alters rather dramatically the
energy flows.

How much power does the source have to supply to
maintain 50 watts of forward power on the transmission
line?


This depends on the design of the generator and the length
of the line. With a shorted line that is 90 degrees long,
and a generator constructed using the circuit of Fig 1-1, the
source supplies no energy to maintain an imputed forward
power of 50 watts on the line.

...Keith