wrote:

Cecil Moore wrote:
A 75m bugcatcher coil used on 4 MHz is NOT significantly below
the self-resonant frequency of 9-10 MHz.

Yes it is, but not so far as to have perfectly equal currents at each
end an zero phase shift in current. It is in the neither land between a
Tesla coil (which is still nothing like my mobile antenna, but at least
getting closer) and a idealized lumped component.

That's about a 99% change in attitude from when we started this
discussion a couple of years ago. At that time you were claiming
that a 75m bugcatcher coil modeled as a lumped inductance with
EZNEC showed zero change in current magnitude and phase and that
was that. I'm glad to see the truth winning for a change.

I think you are going to have to go a *LOT* lower in frequency
than 4000000 Hz before a 75m bugcatcher coil can be treated as
a lumped-inductance.

THE LUMPED-CIRCUIT MODEL FAILS IN A STANDING
WAVE ENVIRONMENT! In the face of that simple technical fact,
all other discussion is moot. Anyone wishing to validly model a
75m bugcatcher coil used on a mobile antenna is forced to choose
a model that does not presuppose faster than light wave travel
through a 75m bugcatcher coil. It's as simple as that.

Nonsense. You are ignoring the coupling mechanisim inside the inductor.

That coupling mechanism works, at best, a lot
lower than the speed of light and only on the voltage. In
a high-Q inductor, the current is known to lag the voltage
by a phase angle approaching 90 degrees. Do you have any
idea what the velocity factor of a 75m bugcatcher coil is?
I'll bet Reg can tell us.

If the voltage is indeed traveling at the speed of light, the
current is known to lag the voltage by a large number of degrees
approaching 90 degrees for an ideal coil. The laws of physics
strikes again. How can you bring yourself to ignore them? The
voltage cannot travel faster than the speed of light and the
current is lagging by, e.g. 60 degrees. It's hard not to suffer
a 40 nS current wave delay through the coil on 4 MHz. I've told
this to you before but you have avoided the subject like a plague.

What you (and the one or two others who seem to agree with you)
repeatedly ignore or forget is magnetic flux couples one turn to
another. A real inductor is always someplace between the two extremes
of something like a radial mode helice (helically loaded whip) and an
ideal lumped component.

You are talking about the E-field, not the H-field. I can agree with
the E-field propagating at the speed of light but the H-field is
known to lag the E-field by an angle approaching 90 degrees in the
limit for an ideal inductor. Or is that another law of physics that
you simply choose to ignore?

Everyone is freely admitting there is *some* transmission line effect
going on. There is some distrbuted component (a series of inductors
shunted by capacitors) going on.

Are you admitting that a 75m bugcatcher coil can be modeled as a
transmission line with a Z0 and a VF? If so, you are giving up
on your lumped-constant model. Actually, since the lumped-constant
model is a subset of the distributed-network model, the lumped-
constant model is very often wrong when the distributed-network
model is correct. OTOH, it is impossible for the lumped-constant
analysis to be right while the distributed-network analysis is
wrong. So much for your choice of models.

Everyone (except you) is being careful to qualify remarks by specifying
the inductor is operating well below self-resonance.

A 75m bugcatcher coil is NOT operating "well below" self-resonance.
It is operating at 1/2 the self-resonant frequency. If one adds one
foot at a time to the stinger above a 75m bugcatcher coil, at exactly
what frequency does it cease to act like a "velocity inhibited
slow-wave helical" and start acting like a lumped inductance? I
propose that frequency is considerably lower than 1000000 Hz.

If you weren't so pig-headed you could look at the measured data at:
http://www.w8ji.com/mobile_antenna_c...ts_at_w8ji.htm

You measured standing wave current, Tom. Your measurements are
meaningless! Standing wave current has the same constant phase
whether the coil exists or not. Your measurements prove absolutely
nothing that is not already known.
--
73, Cecil http://www.qsl.net/w5dxp