Below is my response to an off-list e-mail I received on this topic, which
to some readers may add additional perspective on this topic.

RF

Visit http://rfry.org for FM broadcast RF system papers.
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Thanks for your comments.

The reason I chimed in originally was because of Reg's absolute statement
that preserving system Z throughout the transmission line and its
connectors was unimportant below 1GHz (later 300MHz?). He said further
that an impedance change across a 1" length of transmission line was
irrelevant in that same spectrum.

That is demonstrably untrue, as I pointed out by a real-world example taken
from the broadcast industry.

The net terminating Z of a TV/FM transmit antenna with its input elbows
usually is not exactly 50 ohms, even though that is the impedance value
that the hardware was designed to provide. Manufacturing, assembly and
installation issues can and do change it. The main transmission line
normally is closer to 50 ohms across the relevant bandwidth than the
antenna/elbow termination connected to the far end of that line.

The Z-matching hardware I described is effective at optimizing this far-end
match, it _does_ improve the quality of the radiated signal, and it
minimizes the stress on the main transmission line and the transmitter.
And it does so by changing the impedance in a 1" or less length of
transmission line adjacent to the antenna input, regardless of Reg's
beliefs.

Hams operating on the HF bands may not wish or even need to consider this,
as I mentioned in an earlier post to this thread. But that is not license
for Reg or anyone else to write that such disregard is universally
justified.

- RF