Art wrote:
"So you reject the magnetic field shape of a diamagnetic material as
being different from its steel counterpart?"

Yes. A galvanized tower might just as well be solid zinc due to skin
effect. No one makes any allowance for zinc, steel, copper, or gold
except for resistivity. For that, the adjustment is small indeed.

Further, Maxwell`s equations are ample for all electrical radiation
predictions even though these were made before radio waves had been
discovered. No addenda are needed.

Best regards, Richard Harrison, KB5WZI