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Old August 6th 15, 03:13 PM posted to rec.radio.amateur.antenna
rickman rickman is offline
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First recorded activity by RadioBanter: Nov 2012
Posts: 989
Default Antennas - balanced or not?

On 8/6/2015 9:48 AM, John S wrote:
On 8/5/2015 10:28 AM, rickman wrote:
On 8/5/2015 9:47 AM, John S wrote:
On 8/4/2015 11:31 AM, rickman wrote:
On 8/4/2015 11:39 AM, John S wrote:
The balun thread has become long (138 posts). I propose that we not
discuss baluns, but concentrate on antenna balance and coax
attachment.

Starting from the simplest of all situations, assume a dipole with
an RF
generator in the middle. If we can't agree that this is a balanced
system, then we have nothing left to discuss.

Connect an additional wire to one side of the source so that you have
one wire on one side and two wires on the other side. Is it still
balanced?

Is *what* still balanced? The antenna hasn't changed and is still
balanced.

Well, the starting point is this:

----------0-----------

Where the 0 is the generator.

Then we attach a wire like so:

----------0.----------
|
|
|
|
|

I don't understand how the antenna has not changed.

The generator hasn't changed and is still balanced.

I do not understand how a two-terminal generator can be described as
either balanced or unbalanced.

But you
have added a wire which will load the generator and serve as an element
of the antenna changing the radiation pattern. How significantly the
pattern will change depends on the orientation of the wire and what it
connects to, if anything. There is also the issue of how much
energy is
transmitted along the wire to whatever is connected to it.


Please disregard the radiation pattern in this thread.


If you consider the wire to be part of the antenna, then the antenna has
changed.



In what way could the wire not be part of the antenna?


By your construction. You said you have an antenna and a wire. If you
meant for the wire to be part of the antenna you would have said that in
your OP.


So what is your question?



You will find that in my OP. The question mark identifies it.


"Is it still balanced?" I asked before, what is "it"?

You also said, "I do not understand how a two-terminal generator can be
described as either balanced or unbalanced."

A two terminal generator may have series resistance, for example. That
series resistance may not be evenly distributed. More resistance on one
leg than the other and it is no longer balanced. If the series
resistance is zero, then it would need a *lot* more of it on one leg
than the other.

--

Rick