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Old December 23rd 05, 04:19 PM posted to rec.radio.amateur.antenna
Reg Edwards
 
Posts: n/a
Default Standing Waves (and Impedance)


Roy, you surprise me. Try a jug of Moonshine.

Placing the SWR meter at the start of the feed-line terminated by the
antenna, will tell you NOTHING about the SWR on that line.

It is the antenna input impedance which determines the SWR on the
line, and the meter doesn't have the foggiest idea what THAT is.

The unknown antenna impedance is at the other end of a line of unknown
length, unknown impedance and unknown loss. Unknown, that is, to the
meter.

YOU might have that knowledge. But then you can CALCULATE what the SWR
is on the line. Meter readings having been discarded as useless.

I repeat - the meter tells you only whether or not the transmitter is
loaded with a resistive 50 ohms. No more and no less. If it is not
50 ohms the ambiguous meter will not even tell you the actual value of
Z.

Intoxicated or not, if you insist on a meter reading, there is no
alternative to climbing the antenna mast.
----
Reg, G4FGQ.

PS. The use of SWR by American plug and socket manufacturers to
describe unrelated characteristics of their products is a small
indication of the abysmal depths to which engineering has descended.
Technical specifications are reduced to Camm's Comics. But they look
good to the uninitiated.
----
Reg.
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