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Old June 8th 10, 11:30 AM posted to rec.radio.amateur.antenna
joe joe is offline
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Default Question about "Another look at reflections" article.

Keith Dysart wrote:

These simple thought experiments definitely helped my understanding.
Some of the assertions that have been made can be shown to be false
when tested with these waveforms and analysis.

...Keith



Here is a thought experiment for you.


A C E
+----\/\/\--+--/\/\/\--+--/\/\/\--+--/\/\/\--+
| |
--- -
- ---
| B | D | F |
+-----------+-----||---+---||-----+----------+
| |

Four resistors, equal value.
Four DC sources, equal value.
Voltage A-B = 0, no power past here.
Voltage C-D = 0, no power past here.
Voltage E-F = 0, no power past here.

No power crossing the boundaries on either side of the resistor between
A and C. The resistor is not directly connected to a supply, how is it
dissipating power, if any?

(Yes, I do know the answer.)
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Old June 8th 10, 01:51 PM posted to rec.radio.amateur.antenna
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Default Question about "Another look at reflections" article.

On Jun 8, 5:30*am, joe wrote:
Here is a thought experiment for you.


Does anyone know of a better Google solution to reading an ASCII
schematic than copying from Google and pasting to Notepad?
--
73, Cecil, w5dxp.com
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Old June 9th 10, 12:24 AM posted to rec.radio.amateur.antenna
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Default Question about "Another look at reflections" article.

On Jun 8, 10:30*am, joe wrote:
Here is a thought experiment for you.

* * * * * * * * * *A * * * * *C * * * * *E
* * * *+----\/\/\--+--/\/\/\--+--/\/\/\--+--/\/\/\--+
* * * *| * * * * * * * * * * * * * * * * * * * * * *|
* * * --- * * * * * * * * * * * * * * * * * * * * * -
* * * *- * * * * * * * * * * * * * * * * * * * * * ---
* * * *| * * * * * B * * | * *D * | * * *F * * * * *|
* * * *+-----------+-----||---+---||-----+----------+
* * * * * * * * * * * * *| * * * *|

Four resistors, equal value.
Four DC sources, equal value.
Voltage A-B = 0, no power past here.
Voltage C-D = 0, no power past here.
Voltage E-F = 0, no power past here.

No power crossing the boundaries on either side of the resistor between
A and C. The resistor is not directly connected to a supply, how is it
dissipating power, if any?

(Yes, I do know the answer.)


the first step of the analysis of this circuit is to combine the 4
voltage sources into a single source, thus rendering point b,d,f
irrelevant. you can then analyze for the currents and voltages
through the 4 resistors easily and show that current flows one way
through all 4 of them equally. circuits 101, 2nd day.
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Old June 9th 10, 01:33 AM posted to rec.radio.amateur.antenna
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Default Question about "Another look at reflections" article.

On Jun 8, 6:30*am, joe wrote:
Keith Dysart wrote:
These simple thought experiments definitely helped my understanding.
Some of the assertions that have been made can be shown to be false
when tested with these waveforms and analysis.


...Keith


Here is a thought experiment for you.

* * * * * * * * * *A * * * * *C * * * * *E
* * * *+----\/\/\--+--/\/\/\--+--/\/\/\--+--/\/\/\--+
* * * *| * * * * * * * * * * * * * * * * * * * * * *|
* * * --- * * * * * * * * * * * * * * * * * * * * * -
* * * *- * * * * * * * * * * * * * * * * * * * * * ---
* * * *| * * * * * B * * | * *D * | * * *F * * * * *|
* * * *+-----------+-----||---+---||-----+----------+
* * * * * * * * * * * * *| * * * *|

Four resistors, equal value.
Four DC sources, equal value.
Voltage A-B = 0, no power past here.
Voltage C-D = 0, no power past here.
Voltage E-F = 0, no power past here.

No power crossing the boundaries on either side of the resistor between
A and C. The resistor is not directly connected to a supply, how is it
dissipating power, if any?

(Yes, I do know the answer.)


Very nice. How about:
A C E
+------+--/\/\/\--+--/\/\/\--+----+
| |
| |
| |
| B | D | F |
+------+-----||---+---||-----+----+
| |
In any case, ABCD do not form a network, being, in fact, two
disjoint networks. All bets are off.

Consider:

+------+--/\/\/\--+--/\/\/\--+----+
| |
| |
| |
| B | D | F |
+------+-----||---+---||-----+----+
| | |
-----
---
|
| A C E
+------+--/\/\/\--+--/\/\/\--+----+
| |
| |
| |
| | | |
+------+-----||---+---||-----+----+
| |
There can be current flowing at C and at D, as well as a large
voltage difference between C and D, but these have nothing to
do with each other and are not an indication of energy flow.

For Cecil, using Google Groups, look for 'Options' and select
'Fixed Font'.

....Keith

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