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Old June 7th 05, 02:44 PM
Cecil Moore
 
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Roy Lewallen wrote:

We are not going to get anywhere until you admit there is 68
joules/sec in the feedline that haven't yet made it to the
load. Once you admit that fact, everything else will be moot.

Let's try again. The source is providing 40 watts, 32 watts of which is
delivered to the transmission line. The transmission line is
transferring this 32 watts of power to the load. In the transmission
line, we can calculate that there's 50 watts of "forward power", and 18
watts of "reverse power".


And it is easy to prove that the source has generated 50+18=68
watts that have not been delivered to the load. So I ask
you: Where are those 68 joules/sec located during steady-state
if not in the forward and reflected power waves? Why will
68 joules/sec be dissipated in the system *after* the source
power is turned off?

If those 68 joules/sec that have been generated by the source
but not delivered to the load are not in the forward and reflected
power waves, exactly where are they located? There's really no
sense in continuing this discussion until you answer that question.
Everything else is just a side argument.

The answer to that question will expose the errors in your premises.
You are apparently assuming there is not enough energy in the system
during steady-state to support the forward and reflected power waves.
But that exact amount of energy was supplied during the power-on
transient state and will be dissipated during the power-off transient
state. If it's not in the forward and reflected power waves, you
are going to have to store it somewhere else. Where is that
somewhere else?

The source has supplied 68 joules/sec that has not reached the
load. The forward and reflected power waves require 68 joules/sec.
That you don't see the logical connection between those two equal
energy values is amazing.

But I will get you started on an understanding of the component
powers using an S-parameter analysis.

How much of that 18 watts of reverse power is
going through the source resistor to reach the source to "engage in
destructive interference"?


reference the S-parameter equation: b1 = s11*a1 + s12*a2

I calculate 11.52 watts. (s12*a2)^2 = 11.52 watts

The other 6.48 watts are in (s22*a2)^2 where |a2|^2 = 18 watts

What does it interfere with?


From the S-parameter equation above, it obviously interferes
with s11*a1 .

Please reference HP App Note 95-1, available on the web. It should
answer most of your questions, in particular pages 16 & 17.
|a1|^2 = Power incident on the input of the network
|a2|^2 = Power incident on the output of the network
|b1|^2 = Power reflected from the input port of the network
|b2|^2 = Power reflected from the output port of the network
--
73, Cecil http://www.qsl.net/w5dxp


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