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Old May 23rd 04, 02:28 PM
Richard Fry
 
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Reg:

Consider a signal generator connected through a circulator to the input of a
slotted line. The circulator provides a constant impedance to the signal
generator no matter what impedance is connected to the output port of the
circulator. Now, if your quote below is true, please explain the standing
wave pattern measured via the slotted line probe whenever the slotted line
itself is terminated in other than its characteristic impedance.

Also ponder this scenario. A transmitter is adjusted to deliver the maximum
output power of which it is capable (limited by its power supply) into a 50
ohm transmission line several wavelengths long, terminated in a 50 ohm
antenna. The transmission line is just barely rated to handle the power
delivered by the transmitter under these conditions.

Now something fails within the antenna, and its input Z rises to 2000 ohms.
If the transmitter has no protective circuits to shut it down, it will
continue to generate power, and the transmission line will arc/burn. Of
course, so might the tx output circuits, but let's say they are "very
robust," and the tx continues to operate.

What is the source of the additional power causing the line failure? The tx
already was delivering all the power it could before the failure, so it
isn't coming from there.

RF

Visit http://rfry.org for FM broadcast RF system papers.

____________________

"Reg Edwards" wrote
Reflected power is a mere fiction. Power which is not radiated
from an antenna never actually arrives there. In fact it never
leaves the transmitter.