On 12/28/16 5:51 AM, Patrick Greenlee wrote:
Skin effect... If skin effect can force conduction into the outer limit
of the wire (the chemically altered part with poor conductivity) then
why doesn't the skin effect force conduction out into the insulation and
really have poor conduction? (or in bare wire out into the surrounding
air)
My friend and guru (who refuses to post here) has been a ham for several
decades, is a retired EE, and has 35+ years antenna design experience
(his specialty) agrees with the concept that RF conductivity can be
characterized as a collection of parallel impedances, a continuum
actually. The depth of penetration of RF in a conductor does not have a
"magic" cut-off point but instead has an exponential extinction. That
is, the deeper into the conductor the less RF but there is no magic
barrier preventing RF from penetrating to any arbitrary depth, although
at rapidly reduced values.
Exactly this..
Skin depth is a convenient way to measure the exponential fall off: it
is the depth at which if you had a uniform slab of that thickness and
uniform current density it would have the same resistance as an
infinitely thick slab..
That is: you can calculate the resistance by Skin depth* width * length
* resistivity.