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Old August 19th 03, 07:25 PM
Tom Bruhns
 
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Everything's fine down to point 8, but it's for a line with loss, and
therefore with a characteristic impedance which is reactive, that you
get magnitude of rho greater than unity. You have all the info you
need to show that to yourself with the first few points and additional
fact that load current equals the sum of Ifwd and Irefl at the load.
Just work through the simple algebra to verify the well-known equation
for Vr/Vf, and then plug in Zo = 50-j5 and Zl = 1+j100 and evaluate
the magnitude of Vr/Vf at the load.

Cheers,
Tom

(Richard Harrison) wrote in message ...
Dr. Slick wrote:
"Therefore, the reflected voltage can never be greater than the input
voltage for a passive network, and the reflection coefficient can never
be greater than 1 for such a case."

Terman, despite Reg`s disdain for experts, seems to agree with Dr.
Slick. Here is Terman`s gist:
1. The reflected wave is identical to the incident wave except it
travels toward the generator.
2. Ereflected / I reflected = -Zo. Just as Eforward / I forward = Zo
3. Line loss causes the reflected wave to decline as it travels toward
the generator.
4. Phase of the reflected wave drops back as distance back from the load
increases.
5. Volts at the load are the sum of the incident and reflected wave
volts. Likewise for currents.
6. E/I at the load equals Zload.
7. The vector ratio Ereflected / E incident erquals rho, the reflection
coefficient..
8. In a lossless line, rho is the same everywhere on the line.
9. The effect of a reactive load is merely to displace the SWR pattern
on a transmission line.
There is no opportunity in the stated conditions on a transmission line
for a reflected voltage to exceed the incident voltage or for the
reflection coefficient to exceed one (1).

Best regards, Richard Harrison, KB5WZI

 
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