View Single Post
  #68   Report Post  
Old May 23rd 06, 06:18 PM posted to rec.radio.amateur.antenna
 
Posts: n/a
Default FIGHT? Here is another W8JI myth bone!


Roy Lewallen wrote:
Richard Harrison wrote:
Gene Fuller wrote:
"Terman certainly did not deny the existence of skin effect that keeps
fields out of the interior of conductors.'

true. The point is, shielding from magnetic fields is different from
electric fields. On page 35 of his 1955 edition, Terman writes:
"Magnetic flux in attempting to pass through a shield (copper or
aluminum) induces voltage in the shield which gives rise to eddy
currents. These eddy currents oppose the action of the flux, and in
large measure prevent its penetration through the shield."
. . .


Am I mistaken, but is this not a clear statement that a copper or
aluminum shield will block magnetic flux, along with an explanation of
why it happens?

Roy Lewallen, W7EL


It would only be a clear statement to those who understand what was
quoted from Terman.

If a person is confused by or somehow DOESN'T understand what Terman is
saying, he or she might take it to mean magnetic fields can travel
unimpeded through a shield.

It sure is difficult to drive a stake through the heart of myths like
the loop shield "shielding the electric field and not the magnetic
field" when clearly written text in dozens of engineering textbooks is
misunderstood.

73 Tom