On 11 Jul 2006 12:21:06 -0700, "
wrote:

I wanted to know what the current was in the center conductor of a
piece of RG-8 being used as a monopole. The answer to that question is
not trivially calculable, though it might be trivial in the sense of
being trivia... who cares? I did.

Dan

Hi Dan,

All the issues you focus on are quite particular and specific, and
perhaps too much so. I find them equally interesting and you ask
reasonable questions. Unfortunately, you question above suffers from
every problem imaginable for measuring, and any report you get without
considerable qualification is probably sheer fancy. It suffers from a
version of Heisenberg's problem of disturbing what you attempt to
measure, and invalidating everything in the process.

Another way of stating this problem, with more practicality, is that
you have to put a wire into the coax to add your meter to make the
measurement. This then brings that wire's own contribution, which, as
you've noted, can raise the stakes considerably.

I, too, have played with a variant of your model (I can push the mesh
finer and have worked with a 16 sided coax model). However, instead
of driving the line like a monopole, I simply plunked a source into
the wire skeleton of the "shield."

But to return to your own published model, I've played with the length
of wire 26 after discovering it emerged from both ends of the coax. I
don't put much credit to Cecil's invention of topics, so I am unaware
if this wire length meets some criteria (even if it did, I would still
suspect the detail would have been spurious). Be that as it may.
After truncating the wire 26 so that it did not come anywhere closer
to the mouth of the coax (either end) than 5 feet, "induced" currents
plummeted like a rock.

73's
Richard Clark, KB7QHC