Art, KB9MZ wrote:
"Can I assume then that broadcast coupling coils are always apart to
accommodate a Faraday shield between them?"

This is not an FCC requirement, I Believe. The FCC sets a low allowable
harmonic content level for broadcast signals. A Faraday shield between
coils eliminates capacitive coupling between them.

Capacitive coupling between coils favors harmonics, as capacitive
reactance is inversely proportional to frequency. Killing capacitive
coupling is effective in eliminating harmonic radiation. Putting the
Faraday shield in the tower coupling makes a powerful lightning
deterrent, too.

The usual shield construction is a metal picket fence with the coils on
either side sharing an axis.

Best regards, Richard Harrison, KB5WZI