You're correct that CB whips, 2 meter whips, AM broadcast towers, and
the like are just fine because of their large diameter.

But think about it a little bit. If you reduce the frequency by a factor
of two, the length of a resonant antenna increases by a factor of two.
The skin depth decreases by a factor of the square root of two, so the
resistance per unit length increases by this factor. So at half the
frequency, the resistance of a resonant antenna has increased by the
square root of two. Furthermore, you don't typically use 1/4 inch
diameter wire for an HF dipole, for example. (And most hams presumably
wouldn't make an HF dipole from surplus broadcast towers -- but then I
haven't seen your station.) Assuming you're using a resonant antenna of
constant diameter, the loss gets higher as the frequency gets lower.

Now go back and read what I wrote. Notice that I said that the wire was
most likely to be a problem with antennas on the order of an 80 meter
dipole length. Now you understand (I hope) why that qualification.

If you use an antenna at a frequency higher than its primary resonance
(such as a 40 meter dipole on 15, or a G5RV on a high frequency band),
the loss gets greater yet, since the skin depth decreases with frequency.

Roy Lewallen, W7EL

Richard Harrison wrote:
Roy, W7EL wrote:
"Some stainless steels are ferromagnetic, with a permability I`d guess
at 100 or more. That reduces the skin depth, and therefore increases the
RF resistance by a factor of 10."

Being ferromagnetic does not disqualify an antenna material. Most CB
whips are stainless steel. They aren`t too lossy because they are only
about 1/4-wave at 27 MHz and must be large enough in diameter to be
durable. In the range of 0.55 MHz to 1.7 MHz, most transmission is from
ordinary non-stainless steel towers. The only coating on many of these
is paint. The cross-section to length ratio is economically small, but I
doubt the loss added by using nonplated steel could be measured.

Best regards, Richard Harrison, KB5WZI