As we know, a "transmission line" is a cable to deliver RF output from a transmitter to an antenna.
Part 15.219 limits the length of any transmission line as part of the 3-meter limit also including ground lead and antenna, and my question is:
Why does the FCC place a limit on the length of an AM transmission line in 15.219?
As an academic question, if a transmission line was to be used to deliver RF output from an indoor AM part 15 transmitter to an outdoor 3-meter vertical antenna,
What would be a practical limit in length of the transmission line to achieve good performance?