measures wrote:
>>My next question is: Given, say, a 100 ohm resistive antenna impedance
>>(at the antenna terminals) connected to (assumed lossless) 50 ohm coax
>>line, of multiple wavelengths, (producing a 2:1 SWR) What is the most
>>extreme feed point impedance swing in the line and how far down the line
>>is it?
>> And how can one compute this mathematically, if one does not have
>>access to a smith chart?
>>
>? My guess is that a quarter wave 50-ohm line would transform the
>100-ohms to [100^2 + 50^2]^0.5 =[10k + 2.5k]^0.5 = 111.8-ohms. However,
>with a half wavelength of any Z coax, the 100-ohms would not be
>transformed.
Your GUESS? YOUR GUESS?
Via the Smith Chart, one can easily see that traveling on a constanct
VSWR circle from the load clockwise to the source that 1/4 wavelength
trip will put you at the 25 Ohm point (assuming 50 Ohm normalization).
It is impossible for the real part of the impedance to be greater than
100 Ohms.
73,
Jon
KE9NA
-------------------------------------
Jon Ogden
KE9NA
http://www.qsl.net/ke9na <--- CHECK IT OUT! It's been updated!!!!!
"A life lived in fear is a life half lived."
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