Richard Harrison wrote:
Tom, W8JI wrote:
"Thinking the inductor or loading coil represents 60 degrees of
electrical length is EXACTLY where the big myth is at and it can easily
be proven to be a myth!"

Suppose the vertical is only 2/3 the height needed for self resonance,
or 60-degrees high. The loading coil must replace about 30-degrees of
missing antenna to bring the vertical to resonance.

The myth is in thinking your 60-degree vertical is 90 degree resonant
by virtue of an inductor "replaces about 30-degrees of missing
antenna".

It does not do that.

Every real-world inductor behave to some extent as a transmission line,
but unless the inductor is spatially large in terms of wavelength or
unless the inductor has a termination impedance significantly higher
than the shunting impedance caused by its own self-capacitance to the
outside world the "transmission line" or radiation mode effects are
negligible.

The ultimate in misunderstanding is when people think the loading
inductor replaces a missing electrical degree length, rather than
understanding a reasonably compact inductor primarily inserts a
reactance that compensates for the capacitive reactance of the antenna
system. Does it have some other behavior based on the fact it is less
than perfect? Of course. No one is saying it doesn't have some limited
effects!

If I have a 10 degree tall base loaded antenna it is a ten degree tall
antenna. It is NOT 90 degree resonant antenna with "80 degrees of
missing length" in the inductor, nor with that 80 degree long inductor
behave like 80 degrees of antenna length would.

The very incorrect concept that an inductor and loaded antenna acts as
a "80 degree coil and ten degree antenna" (substitute the numbers you
want) is what kicked this whole thing off several years ago.

73 Tom