You are moving towards my theory on this, Tim.


On Fri, 15 Jun 2007 20:24:33 -0500, Tim Daneliuk
wrote:

Tim Daneliuk wrote:
Tom Watson wrote:
There have been a number of responses so far, many of which reference
the "skin effect" - why the hell do we continue to produce wire that
has a core of the same conductive capacity as the surface, at great
cost, when we might manufacture a wire of a cheaper core material,
with the surface conductor at optimum.?



I think this is all about frequency. At 60hz I don't believe this
buys you much, but at Mhz/Ghz freqs it might ...


Oh, in a related note ... In my misspent youth, I installed/repaired
High Frequency Single Sideband Radios for fishing boats in Alaska.

Many of these vessels were wooden and ground is rather important when
designing HF radio antennas. We could typically find good ground at the
heat exchanger in the bilge of the ship which was metal and in contact
with the ocean.

The problem always was that these are typically pretty far away (20-100
feet) from the wheelhouse. If we used wire to get to ground, that wire
then actually became a radiator of radio energy - which is not what you
want from a ground.

So, we used copper flashing which was very thin but *Wide*. At HF
frequencies, area turns out to be a big deal for ground planes. In the
worst case, we'd use 00 or even 0 welding cable to get to a real ground
because - IIRC - the effective area of a wire is something like 2-3x its
diameter.
Regards,

Tom Watson

tjwatson1ATcomcastDOTnet (real email)

http://home.comcast.net/~tjwatson1/