Pete,
Well, long ago, someone advertised that they used stranded wire in their
product because of its superiority, and those who bought it, also bought
the line and invented reasons why stranded was better.
At most, stranded wire of the same gauge and drawn to the same degree of
hardness has a slight strngth advantage over solid, since a nick usually
is confined to one strand of the collection. In return, the individual
strands of stranded puncture the fingers of hams with greater regularity
than solid to the tune of about 10 quarts of collective blood to 1.
At low frequencies, there is Litz wire, out of which comes some of the
stranded mythology. Except that Litz is insulated strand by strand.
Except that the advantage of Litz disappears at about 0.5 MHz (some say a
bit higher, some say a bit lower, but no body says it is any good at HF
and up).
Some argue that stranded has a higher surface area than solid, but that
is to misunderstand not only HF but RF current in an antenna. AC sets up
a constantly changing field around the wire yielding skin effect or ever
decreasing current penetration with increasing frequency. The two are
closely related in many ways. The inner wires of stranded wire are as
current-free as the depths of a solid wire. The field will not let all
the bumps and valeys play a role in the apparent surface area, but keep
the current at about an average for the bumps and valleys measured at any
cross-section. Hence, there have been--for solid and stranded of equal
materials--no reports of significant differences in either DC or AC (HF
RF) resistance.
If stranded were in any way electrically superior to solid wire as an
antenna element, there would be a significant difference between
otherwise identical wire elements of each material in the current level at
any point along a wire antenna (dipole, for instance), for that is the
only way to get a greater far field. For a given power, that would mean a
lower feedpoint impedance. Neither of these effects have ever been
reported in any of the literature I have encountered. Since P = I^2*R, a
small change in I would show up as a larger change in R for a given power,
and so the phenomenon would not be missed.
I do not know the terms of the .rec discussion. However, I know of
nothing that would, should, or could make more than an absolutely
miniscule electrical difference between solid and stranded wire of the
same material and same gauge at HF as an antenna element.
Hope this is useful, but please do not replay it on the .rec. I have no
desire to get involved in the mode of disputation that occurs there.
I much prefer it here, where, when folks say "happy holidays," they mean
it.
Happy holidays.
-73-
LB, W4RNL
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