Reductio ad absurdum - short antennae do not radiate well
"gareth" wrote in message ...
Consider 100W at 3.6MHz propagating along some 50 ohm
coax, which terminates suddenly but with 1/4 inch of the central
conductor protruding.
Now there's no difficulty in feeding all that power into that
1/4 inch because it is so short compared to a wavelength
that there is a uniformity of voltage and current along it,
and it will be essentially the same as that existing in the last
gnat's cock of the coax.
Attach a hi-impedance scope probe to the end of that
1/4 inch and all the power being delivered through the
coax will be detectable right at the tip of that 1/4 inch.
Now, will that 1/4 inch antenna radiate all the power that
is being successfully fed to it at 3.6MHz, or will the
configuration behave merely as an open-circuit with all
the power being reflected back down the coax?
A number of contributors to this NG claim that the 1/4 inch
stub antenna will radiate the full 100W at 3.6MHz,
snip
In this example, the transmitter delivers 100w to the coax, but only a small
part of that is delivered to the 1/4 inch "antenna".
The 1/4 inch will radiate the power delivered to it just as well as a to a
full sized antenna.
Matching and radiation are two different subjects.
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