On Apr 23, 9:21*am, Cecil Moore wrote:
Art Unwin wrote:
The problem *in this debate is that others are concentrating on
resonance
where as you are thinking in terms of anti resonance which portends to
a higher impedance and also the condition of equilibrium.

I apologize if I gave you that idea, Art. I am talking
about a physically short (38 degrees), electrically 1/4WL
(90 degrees) *resonant* antenna over mininec ground. The
feedpoint impedance is low and resistive.

In the example given, the stinger supplies 19 degrees
of phase shift, the base-loading coil supplies 19 degrees
of phase shift, and the impedance discontinuity between
the coil and the stinger provides a point phase shift that
makes up the difference between 38 degrees and 90 degrees.

As I hammer away at this concept, I am wondering if a
loaded mobile antenna can be optimized if only the correct
model is adopted. Is a high-Q loading-coil always better
than a loading-coil with a lower Q? Are fat/short loading-
coils always better than skinny/long loading-coils? Some
field measurements have cast doubt on some long-held
concepts.

But obviously the question cannot be answered as long as
some people insist on using the lumped circuit model for
the loading coil, e.g. virtually zero delay through the
coil.

I have measured the delay through a 75m bugcatcher coil.
It was approximately 25 nS, a magnitude greater than
w8ji's "measurements". It doesn't matter if my measurements
were off by 20%. The magnitude difference between my
measurements and w8ji's "measurements" is too significant
to be ignored.
--
73, Cecil, IEEE, OOTC, *http://www.w5dxp.com

Exactly. !/4WL is not in equilibrium,a full wave length is and that is
where you are argueing past each other. Radiation is the accelleration
of a charge or a particle of energy. A half wave accelerates a charge
and the second half replaces the static particle that created the
facilities for the next radiation or application of charge.
If you only use a portion of the period then you are messing with the
speed of light.
The speed of light is the time it takes for a magnetic field to be
produced and the time
it takes for a magnetic field to decay which also equals the time that
it takes for an electric field to be formed and decay the sum time of
both being a period or the speed of time. Thus a WL is equal to
equilibrium and less than that is not. Maxwells laws are valid ONLY
when equilibrium is present, thus the quarrelling between the two
parties.
Embroiled in the middle of that is the misconception of standing
waves.
A charged particle changes direction and then returns to the starting
point to constitute
a full period. If you have a 1/4 wave the charge continues its
direction until half a period has passed and only then can particles
be collected for sunsequent acceleration and radiation. So for half
the time or 1/4 of the time for a 1/4 WL is the radiating at an angle
i.e the addition of two vectors,forward and displacement current,
the rest of the time the remaining charge is the accelleration of the
charge continuing
off of the end of the radiator ( not bouncing back) where the energy
is seen as a spark
or straight line radiation. So Cecil the debate in fact is over a
series of misconceptions resulting from the omission of equilibrium
which makes both sides of the debate invalid.
Regards
Art