Author Topic: WTF [E9F13(2008)]  (Read 4467 times)

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AD

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WTF [E9F13(2008)]
« on: March 29, 2012, 04:30:41 PM »
 What kind of impedance does a 1/4-wavelength transmission line present to a generator when the line is shorted at the far end? [E9F13(2008)]

A very high impedance  Correct!

Can someone versed in this theroy explain this to me please?  If it was open it should be high(infinite) shorted should it not have a low impedance?

Here is the 1/2 wl version

What kind of impedance does a 1/2-wavelength transmission line present to a generator when the line is shorted at the far end? [E9F14(2008)]
A very low impedance  Correct! 
« Last Edit: March 29, 2012, 04:41:34 PM by AD »
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spacecase0

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Re: WTF [E9F13(2008)]
« Reply #1 on: March 29, 2012, 05:02:04 PM »
shorted or open the impedance is high because all the voltage is reflected in 1/4 wave or shorter line,

maybe this will help,
as the wave travels at 1/4 wave away the voltage is at the highest point, when it gets back to 1/2 wave the voltage is at the lowest point, and it keeps going like that in the line

AD

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Re: WTF [E9F13(2008)]
« Reply #2 on: March 29, 2012, 05:06:37 PM »
Thanks space

I was thinking DC voltage and not a wave function. I guess the wavelength word shold have give me a hint  ::)
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idial1911

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Re: WTF [E9F13(2008)]
« Reply #3 on: March 29, 2012, 05:46:16 PM »
Thanks space

I was thinking DC voltage and not a wave function. I guess the wavelength word shold have give me a hint  ::)

Actually pay attention to that, I am pretty sure they ask that exact same question except swap wavelength out with voltage or something like that to try and trip you up.
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SigInt

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Re: WTF [E9F13(2008)]
« Reply #4 on: March 30, 2012, 12:53:16 AM »
I remembered that 1/4 wave was opposite day and then I asked why after I passed the test. :)
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KC9TNH

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Re: WTF [E9F13(2008)]
« Reply #5 on: March 31, 2012, 06:53:09 PM »
shorted or open the impedance is high because all the voltage is reflected in 1/4 wave or shorter line,

maybe this will help,
as the wave travels at 1/4 wave away the voltage is at the highest point, when it gets back to 1/2 wave the voltage is at the lowest point, and it keeps going like that in the line
Your description is elegant in its simplicity - thank you. Something buzzin' in my head is about to make some sense. Time for a Coke and a plate full of taquitos.
 ;D