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Old September 1st 05, 09:18 AM
Roy Lewallen
 
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If anyone besides me is having trouble keeping track of what Reg is
trying to say, maybe the following recent quotes will help. That is,
they'll help you understand why you're having trouble keeping track.

For what it's worth, I agree with the first quotation of 8/31. But
apparently Reg doesn't, even though he said it.

Roy Lewallen, W7EL

8/30:

Perhaps somebody might be prepared to state the power actually
radiated from feedlines in watts. At least it may create the
impression you know what you are talking about.

8/30:

Roy, do everybody a favour, by stating, numerically, how much power is
radiated from feedlines. Then somebody might have some confidence in
what you are bafflegabbing about.

8/31:

Any current which finds its way on to (3), which ought to flow in the
antenna, will result in the coax participating in the radiation
pattern of the whole antenna structure.

BUT IT IS A SILLY QUESTION TO ASK HOW MANY WATTS ARE RADIATED FROM THE
FEEDLINE.

OR, CONVERSELY, HOW MANY MICROWATTS ARE PICKED UP BY THE FEEDLINE ON
RECEIVE.

The feedline cannot be treated in isolation as if it behaves
independently of the antenna. For starters, the radiation resistances
of the feedline and antenna do not add arithmetically. They interact
with each other.

8/31:

If you erect a 10 meter 1/2-wave dipole and center-feed it with a 50
feet length of coax, and then transmit on 1.9 MHz, 99.9 percent of
available power will be radiated from the feedline and only 0.1
percent from the antenna itself.

http://www.smeter.net/feeding/feedpowr.php:

Centre-Fed Dipole - Radiation from Coaxial Feedline
Author: R.J.Edwards G4FGQ © 25th March 2003

Program Notes
.. . .
With no loss in accuracy, to simplify the model, the transmitter is
located at the dipole centre and the coaxial line is replaced by a
single conductor of the same diameter as the coaxial braid. There are 3
radiating elements. Radiation resistance, input impedance, and input
current of each element is calculated. Finally, the percent of total
power radiated by each of the three elements is calculated.