Aet wrote:
"WHY? beCAUSE THE MAGNETIC FIELD LINES FROM A DIAMAGNETIC MATERIAL SUCH
AS ALUMINUM OR COPPER IS AT RIGHT ANGLES TO THE AXIS OF CURRENT FLOW
WHICH IS NOT THE SAME AS WITH A FERRITE MAGNETIC MATERIAL.

My experience with broadcast towers is that it matters not if a steel
tower is painted or zinc coated it works the same.

Terman`s 1955 opus says on page 21:
"When a current is flowing through such a conductor (he makes no
distinction between iron or copper, but does describe an isolated round
wire), the magnetic flux that results is in the form of concentric
circles, as shown in Fig. 2-9. It is to be noted that some of the flux
exists within the conductor and therefore links with , i.e.,encircles,
current near the center of the conductor while not linking with current
flowing near the surface. The result is that the inductance of the
central part of the conductor is greater than the inductance of the part
of the conductor near the surface; this is because of the greater number
of flux linkages existing in the central region."

Terman is describing "skin effect".

"Right hand rule" definitions also say magnetic flux encircles the
current carrying conductor. Art`s assertion is "off the wall".

Best regards, Richard Harrison, KB5WZI