On 8/9/2015 12:36 PM, John S wrote:
On 8/5/2015 8:47 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.

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?

Well, the starting point is this:

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

Where the 0 is the generator.

So, if any current flows, it will be the same magnitude in each wire
like this:

I - I -
-----------0----------

Then we attach a wire like so:

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


Now, if we have a current in the left-hand side, it MUST be balanced by
the SUM of the currents in the right hand side. Like this:

I(t)- I(1)-
----------0+---------
|
| I(2)
| |
| V
|

So, I(t) = I(1) + I(2)

The point here is that there will be a current (I(2)) in a coax shield
attached to the antenna whether there is a ground connection or not.
There will be a current (I(2)) in a coax shield attached to the antenna
whether the antenna is matched or not. I do not see any other alternatives.

I don't see how anyone could argue against that... although some seem to
based on the idea that because the antenna is "balanced" all the current
will flow equally to both antenna elements and there will be none left
to flow on the shield.

In another group I explained how the the current would flow on both the
antenna element and the shield according to the impedance and one of the
very experienced members replied that I should have been an RF engineer.
lol Seems some folks get this very basic concept wrong.

I think this is an example of how we use many generalizations which only
apply properly under specific conditions which we forget.

--

Rick