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Old July 7th 15, 12:36 AM posted to rec.radio.amateur.antenna
Dave Platt[_2_] Dave Platt[_2_] is offline
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First recorded activity by RadioBanter: Dec 2014
Posts: 67
Default An antenna question--43 ft vertical

The only case I am aware of that will give total reflection is when
the terminal is open circuit with infinite impedance absorbing *no*
signal.

Also when it is a zero impedance (short circuit).


I'm trying to picture this.

In the case of an open circuit a matched driver drives the transmission
line to 50% of the driving voltage. The wave reaches the open
termination and is reflected with the same polarity resulting in a
return wave that reaches 100% of the driving voltage.

In the same vein, if the wave hits the short circuit the reflected wave
will be the opposite polarity making the reflected wave 0% of the
driving voltage resulting in the short circuit eventually showing to the
drive circuit.


Yup. You can see this happen on a time-domain reflectometer (an
o'scope and a pulse generator will do).

(although, to pick nits, I'd clarify your latter paragraph to read
"will be of the opposite polarity, making the sum of the forward and
reflected wave 0% of the driving voltage...")