Richard Fry wrote:
"As a condition of the FCC or other qualification needed to legally
offer the tx for sale, MW broadcast transmitters must meet their
harmonic suppression specs by themselves."

It`s true. They are type accepted and don`t produce excess harmonics at
their outputs. The coupling system does not suppress the fundamental but
may further suppress the harmonics.

I`m sorry to misspeak. Never the less, a capacitor`s impedance is
inversely proportional to frequency. Its elimination as a coupling to
the antenna eliminates a preference for higher frequencies in the
coupling system. A pi or T network with shunt capacitance and series
inductance favors the fundamental frequency over its harmonics. These
aren`t required to meet specs but they further reduce harmonic radiation
from the radio station.

The Faraday screen is common in radio stations. It was put there not to
affect the antenna match but only to eliminate capacitive coupling to
the antenna. It also serves as a path to earth for many antenna
lightning strikes as evidenced by numerous pits and metal hrom them
splashed about the enclosure.

Best regards, Richard Harrison, KB5WZI