[Elecraft] how did I calculate the loss?

[Don Wilhelm]

Vic and all,

I respectfully disagree.  The balance or lack of balance is dictated by the
antenna system itself (and the RF will be independent of grounds).  So, if
the antenna system is inherently balanced, the currents (or voltages if you
prefer) on the feedline will be equal and opposite no matter what the drive
is - this is not dependent on a balun or lack of a balun anywhere in the
system.

Look at it another way - the current at the ends of the antenna must be
zero - period.  No amount of current 'forcing' will change that - mother
nature will have her way in this.  If the antenna is unbalanced, the use of
a balun to "force equal and opposite currents" will only serve to induce
losses elsewhere in the antenna system.

I realize that this is 'flame' territory, but I do not intend it as such.  I
am not saying baluns are not good things, but instead, I am saying that
baluns serve the purpose if keeping extraneous RF currents in their proper
places - they are not the sole element that will determine the current
distribution on an antenna system (and that is what is implied by the
'current forcing' adherants).

The real reason for a balun at the feedpoint of an antenna is to keep the
current from flowing down the outer side of a coax shield.  If one is
feeding an antenna with balanced line, this situation is not present.

At the transmitter (or tuner) end of parallel line, a balun is a 'nicety',
but not a necessity, because the RF will find its own COMMON potential - as
I stated earlier, this really can be independent of any actual ground
potential.  OTOH, if "RF in the shack" is a problem, a balun at the
transmitter (or tuner) output may cure it.

73,
Don W3FPR

----- Original Message -----

> I forgot to add...wouldn't you also need a balun at the antenna
> feedpoint?  If you connect the feedline directly to the antenna the
> currents in the legs of the feedline could be unbalanced and then you
> might have significant loss from feedline radiation.
>