"Richard Fry" wrote in message
...
So the definition of electrical length you use excludes radiation
resistance?

Yes, of course a 60 degree coil obviously doesn't radiate like a 60 degree
piece of wire. The 60 degrees is merely the phase shift that a traveling
wave
current undergoes while traveling through the coil. I hope this is not
just a semantic problem. When someone says a coil replaces 60 degrees
of an antenna, he certainly doesn't mean for radiation purposes (unless
he is an absolute dummy). He simply means the coil causes a 60 degree
phase shift in the forward current, much like a 60 degree length of wire.
And that's all it means.

Model a short vertical radiator in NEC, and check its impedance. If short
enough, it could be something like 0.1 -j2500 ohms. Now add an inductive
reactance to the system to reach resonance. NEC then will show 0.1 +/-0
ohms. Note that the radiation resistance term did not change.

Of course not! Nobody is arguing otherwise. You are obviously confused
about what I, and others, are saying.

That short system is resonant, but it certainly won't have the practical
radiation efficiency of a full, 1/4-wave, linear radiator, even though
they
both have the same "electrical length" by your definition.

Is this a straw man? Nobody has said anything remotely resembling any
argument otherwise. Electrical length doesn't have much to do with
radiation. The radiation resistance and therefore efficiency, is closely
associated with the physical length. Electrical length mainly has to do with
phasor rotation. If a traveling wave current phasor rotates 90 degrees while
flowing through a coil, the coil's electrical length is 90 degrees. That's a
pretty
simple concept. The coil can even be considered to be lossless and non-
radiating in some relatively efficient antenna systems without introducing
much of an error.
--
73, Cecil, W5DXP