On Mon, 2006-05-08 at 10:52 -0400, Martin, AA6E wrote:
> On 5/6/06, Randy Russe3ll <lord_russell53@yahoo.com> wrote:
> >
> > ... I guess when you have a 1 ft. wide sheet
> > of copper for RF usage, it has the same usable
> > conducting area as if you rolled that one foot
> > circumference into about 4" inches wide. So it is
> > effectively the same RF conductor as a 4" dia. piece
> > of copper wire, yes? with lower inductance? Since RF
> > only utilizes the surface of a wire conductor.
>
>
> Yes, a 4" tube of copper flashing is the same at RF as a 4" solid rod,
> because of skin effect. But a 12" flat strap is probably twice as good
> (half the impedance), because current flows on both sides. No RF current
> flows on the inside of the tube.
>
> On the other hand, a 4" bar is a lot less likely to explode or blow away!
In my experience with lightning damage, I've found that only the surface
1/64th inch melts from lighting current while the rest of the conductor
stays solid. The associated magnetic fields push that molten metal out
into tits and fans. That signature is what I use to tell lightning
damage from ordinary power frequency arcing that heats full depth.
>
> 73 Martin AA6E
--
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer
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