On Aug 29, 4:45*pm, Cecil Moore wrote:
On Aug 28, 9:23*pm, Art Unwin wrote:

A long time ago there was a arguement both on this group and on E ham
with respect to the function of a coil with respect to replacing
missing degrees of a wavelength.
Both Tom W8ji and Roy W7EL did experiments which apparently justified
an account written up by Tom under the subject.

I am completely ignorant of your "double helix" so I cannot comment on
that subject. I always thought a double helix was a strand of DNA.

On the subject of the number of degrees occupied by a loading coil,
both Tom and Roy made an incorrect assumption that rendered their
conclusions at best moot, and at worst false. Roy reported no
measurable phase shift in the current through a loading coil and
seemed to support the misconception that the phase shift is
proportional to the delay through the coil, which it is not.

Both Tom and Roy seemed to assume that the antenna current changes
phase by one electrical degree for each physical degree of antenna.
But EZNEC easily proves that to be an incorrect assumption for the
current in a standing-wave antenna which includes dipoles, monopoles,
and loaded mobile antennas. The following applies to 1/2WL dipoles and
1/4WL monopoles including loaded mobile antennas.

THE PHASE OF THE NET CURRENT IN A STANDING-WAVE ANTENNA CHANGES VERY
LITTLE BETWEEN THE FEEDPOINT AND THE TIP END OF THE ANTENNA.

*The phase of that current cannot be used to calculate the delay
through a wire or through a loading coil.* The phase of the net
current in a thin-wire 1/4WL monopole changes by ~3 degrees over a 90
degree physical length. The same is true for a loaded mobile antenna.
Anyone assuming that signal delay is proportional to current phase
shift in a standing wave antenna is off by a magnitude or more. Tom's
reported 3 ns delay through his coil is about 12% of the actual value
of the delay at 4MHz.

The following inductance calculator can be used to estimate the delay
through a loading coil. The parameter to use is the "Beta = rad/m,
Axial propagation factor of n=0 sheath helix waveguide mode at design
frequency[1,8]'

http://hamwaves.com/antennas/inductance.html

The rad/m of the axial propagation factor can be used to calculate the
number of degrees occupied by the specified loading coil and the
velocity factor of the loading coil. The 100T, 10" coil that Tom used
for his "measurements" has a delay of ~30 degrees at 4 MHz, virtually
unrelated to the phase-shift in the standing-wave current that he
reported. Delay is NOT proportional to current phase-shift on a
standing-wave antenna and certainly not for the loading coils on a
standing wave antenna. However, delay is proportional to current phase-
shift on a traveling-wave antenna.
--
73, Cecil, w5dxp.com

but of course we all know that a standing wave is a figment of your
instrumentation!