Agreed except the only properly built and installed antennas exist in
text books and free space. For the antenna itself (forgetting for the
moment the transmission line) it would have to be installed in a
completely balance environment. Yard clutter such as buildings, trees,
powerlines and etc. would have identical geometry in relation of your
balanced antenna - something that does exist in the real world. Plus
ground conditions under and near the antenna will vary. So there will
be some unbalance. Next add the transmission line. Have you ever seen
a ham station whose transmission line ran perfectly perpendicular from
the antenna to the transmitter? In other words, there will be some
unbalance the only question is how much,

73,
Danny, K6MHE






Hi Danny:

You are of course correct, but with RF in the shack problems levels are
important. If the level of RF is below some threshold it causes no harm.
Almost all Ham stations operate just fine with low levels of unbalance
and other defects in the antennas.
Just for interest sake I ran some numbers on a model ground system. Let’s
assume you have a perfect ground system and you connect to it from the
shack on the second floor using 12' of #6 wire. And it runs in a straight
line, no bends or curls. The self inductance of that wire is about
56.22uHy.
So what will be the reactance of that wire at 3.5 MHz? Doing the math I
get 1,235.7ohms. At the other extreme 28MHz, I get 9,886.52ohms. These
are numbers that hardly make me confident that I have any kind of a RF
ground.
By the way at 60Hz the reactance is 0.021ohms that I think is a good
ground.
Please excuse me for harping on this, but I run the electronics shop in
the Physics dept at Penn State University. I'm constantly seeing many
meter long thin wires tied to some cold water pipe or something in a lab
that is supposed to get rid of all the high frequency noise in some
experiment and it has no chance of helping. If physics grad students have
problems understanding grounding it's no wonder that Ham’s do too.

John Passaneau W3JXP