"Ian White GM3SEK" wrote in message
...

From the beginning, then:
snippydidudaa

As we have seen, if the whip is loaded by pure inductance only, there is
no change in current between the two terminals of the inductance - but
there's a big step increase in voltage. At the upper terminal, the current
is the same but the voltage is very high, so we're into a much
higher-impedance environment.


Reality check here. I need explanation how the above could happen. "Current
stays the same ... and the big step increase in voltage." As far as "idiot"
professors taught me, (current x voltage) = power. So, am I to discover
that the pure inductance is better than perpetual motion amplifier of power?
More power coming out of the coil than going in? Eureka!!! How could I
overlook that? :-)

As we go further up towards the top of the whip, current magnitude has to
taper off to zero at the very top. This also means that the voltage
magnitude has to increase even more as we approach the top of the whip.


So it tapers across the straight piece of conductor, but not in the wound
up conductor? Magine that! Reality check #2.

Single-point loading by pure inductance has thus created almost all the
major features that we see in a practical centre-loaded whip -
particularly the big step change in voltage across the loading coil.


So the "teaching" is that there is a big step change in the voltage across
the coil, but no-way change in the current? Who's law, theory, invention is
that? (We are still talking about real RF currents, not "my voltage" and
"your invincible, steady, unchengeable current"?)


What we don't see in a practical antenna are exactly equal current
magnitudes and zero phase shift between the terminals of a real-life
loading coil - but that is ONLY because a real-life coil is not a pure
inductance. The harder we try to reach that ideal (by winding the coil on
a high-permeability toroidal core which confines the external fields and
allows the whole thing to become very small), the closer the currents at
the bottom of the coil come to being equal. Solid theory and accurate
measurements come together to support each other. The only gap between
theory and practice is due to our inability to construct a pure inductance
that has no other complicating properties.


The whole argument is about REAL LIFE loading coil in the antennas. But you
obviously ignored or not noticed that W9UCW also used toroid coil and found
very similar results, about 40 - 60 % less current at the top end and NOT
(just about) EQUAL as the arguments IS about. Who cares about or needs
"pure" inductance? What for? Just to twist the argument that "gurus" were
right? Gimme a break!

If we can agree about pure inductive loading, we all have a firm place to
stand. Then we can then put back those "other" complicating properties of
a real-life loading coil, and see what difference they make.

As firm as driving my Buick in the free space!
Halooooo! Go measure it! See what it IS! Then if the coil IS hot at both
ends, or you measure current almost equal at both ends, describe the
experiment so we can verify it and we will rest our case and admit to be a
bunch dummies stuck on stooooopid!
(We are still talking about quarter wave resonant, loaded typical mobile
antenna with loading coil about 2/3 up the 8 - 10 foot mast, no detours to
la-la pure inductance in the vacuum with no resistance, free space
no-nothing thing :-)
And as Cecil mentioned, we are not disputing that there is no capacitance to
the surroundings, or no losses through resistance and radiation amounting to
SMALL (you put figure on it Richard) drop, versus more SIGNIFICANT (like
40 -60%) drop across the loading coil.

I am sorry to beeing away for a zilion of posts, but real life is more
important and I am trying to be in touch. I will try to find the W8JI
response to my first (start from scratch) post in order to find where I went
wrong, if he will engage in some technical discussion. I hate to be wrong.

Happy second April foolsday!

Yuri, K3BU.us


[1] This principle of "conservation of charge" is also the underlying
principle of Kirchhoff's current law. If you connect three ordinary wires
together, the current flowing into the junction from one wire must be
exactly and instantaneously balanced by the currents flowing in or out on
the other two wires. If this was not so, there would have to be some means
of adding, storing or losing electrons at the junction... which
contradicts our initial assumption of three simple wires with no special
properties.

It is not strictly accurate to say that Kirchhoff's current law applies to
pure inductance, but the underlying principle of "conservation of charge"
does apply.
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek


What "other two wires"? I see RF current flowing through one wire (base)
then another wire in series (coil) than another one in series (tip - whip)
then "finding" the tip, aka END reflecting form it, and going back, creating
standing wave with proper current AND voltage distribution according to sine
(or if you like cosine) function.
What about energy (power) conservation law? How can coil "make" more voltage
at the top, while "having" the same current on the top as at the bottom?

73 + 88 from Yuri K3BU, jus' inquiring mind