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Old July 9th 15, 06:39 AM posted to rec.radio.amateur.antenna
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Default An antenna question--43 ft vertical

John S wrote:
On 7/8/2015 4:52 PM, wrote:
John S wrote:
On 7/8/2015 1:18 PM,
wrote:
John S wrote:
On 7/7/2015 1:52 PM,
wrote:
Brian Reay wrote:

Do the experiment.

Did it decades ago in electromagnetics lab with calibrated test equipmemnt,
not with amateur radio equipment.

Post the original lab notes, please. That way we cannot challenge the
accuracy of your memory.

Sorry, that was decades ago.

If you are so convinced, do the experiments yourself and post the results.

Or you could read an electromagnetics text on transmission lines and
show me the errors of my statements.

I did, decades ago. The results are that you are wrong. You surely trust
my memory as well as I trust yours, yes?


What I trust is what I can read in an electromagnetics text.


Fine. Then you should confine your arguments to those sources rather
than referring to decades old measurements to you may not remember
correctly.


Instead of arguing about it, one can download QUCS for free which
will simulate the whole thing and one can see what really happens.

Download QUCS for your operating system:

http://qucs.sourceforge.net/

Generate a model consisting of a voltage source with a series resistance
of a few Ohms to simulate a solid state source or a much higher
resistance to simulate a vacuum tube source. Chose a convienient
frequency for the simulation.

Go to: http://home.sandiego.edu/~ekim/e194r.../matcher2.html
to calculate an impedance matching network to match the resistance
you've chosen to 50 Ohms at the choosen frequency.

Put the matching circuit in the model.

Add a 50 Ohm transmission line to the model.

Terminate the transmission line with a 50 Ohm resistor.

Add a fixed frequency AC simulation at the choosen frequency.

Change various parameters to your heart's content to see what happens.

Change the matching network such that the output of your transmitter
is no longer 50 Ohms and see what happens.

When the QUCS output disagrees with your beliefs, you can argue with
the program.


--
Jim Pennino
 
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