Richard Hry wrote:
"---MW broadcast Antenna Coupling Units commonly do not contain Faraday
screens."
My observation is from a previous century. Faraday screens were used in
stations in which I worked.
My response was to the question: Can the E and H fields be separated?
Yes they can, and the Faraday screen is a way to eliminate coupling the
E field while coupling the H field. On the decoupled side of the shield,
induced magnetic lines immediately produce electric potential
differences and E fields. Little changes and nothing has been lost
except for capacitive coupling between circuits on opposite sides of the
Faraday screen. Breaks in the screen prevent circulating current which
would generate opposition to magnetic coupling. This is demonstrated as
effective since ancient times in electricity. Electric lines find a
ground return in the Faraday screen and go no further.
A shield without breaks allows current circulation which generates an
opposing force (Lenz`s law) and nullifies the induction. The continuous
conducting screen also provides a grounded termination for the electric
lines and blocks their passage too.
Capacitive coupling through a hole in a continuous shield can allow the
E field to be coupled while eliminating magnetic coupling.
This does not say there is any merit to the E/H Antenna, about wehich I
am ignorant.
Best regards, Richard Harrison, KB5WZI
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