Yuri Blanarovich wrote:
Howdy Antenna NGers,

I took the time to check out the Helix feature in EZNEC 4.08 and modeled the
"worst" case - CB whip or 10 m whip with loading coil - helix half way up and
then the same helix moved up to 3/4 way up. Things will get more pronounced
when more turn, more inductance coil is used and frequencies are lower. Yes,
Virginia there is a CURRENT DROP across the loading coil, unless you have more
"appropriate" or "scientwific" term for it.

Rough dimensions: 1m mast (5 mm copper wire/tubing), 20 cm long coil/helix with
5 cm diameter turns, 5mm wire diameter, 10 turns, spacing 2 cm followed by 1 m
whip
Resonated at 27.05 MHz
With base current 1 A, at the end of mast/start of coil the current is 0.87457
A
at the end of coil/start of whip the current is 0.66884 A - a decent drop of
0.20573 A or 20.5 % - not an "EQUAL" (you DC coil believer types!!!)

Then I moved the same coil up 50 cm, so the mast was 1.5 m, same coil, followed
by .5 m of whip.
Again with base current of 1 A, the bottom of the coil had current this time
was 0.65479 A, while top of the coil 0.37127 with larger drop of 0.28352 A or
28.3 % - even bigger not "EQUAL" with resonant frequency moving up to 28.7 MHz,
which corresponds to REALITY measured, experienced and finally properly (close
enough) modeled. Even M0RON (with apologies if there is call like that issued
:-) can see the nice current drop across the coil displayed in the VIEW.

Thank you Roy (now you believe it?), Cecil, Richard. Now the unbelievers can
even model this case themselves and SEE it properly. So ON4UN, K3BU, W9UCW,
W5DXP, KB5WZI were and are right. W8JI, G3SEK et al are sooooo wrong :-) Some
still persist, some are converted and many will be enlightened.

Now if Roy can incorporate elegant way of modeling real life coil/inductance by
inputing Inductance L and its physical size and have it calculate things
without modeling turns, that would be a winner and a segment saver.

So after all, those "dumb" hams pointed out 50 years of misinformation in even
ARRL "bibles" like Antenna and Handbooks :-(yep, latest 2005 "revision" still
has it in it)

Just watch W8JI to massage his web page and twist out of this one (yet another
egg in the face :-)

Yuri Blanarovich, www.K3BU.us
www.computeradio.us

There may be a difference in current along the coil, but it isn't a
current drop. There is no such thing as a current drop in the sense
people use when they say "voltage drop." By the way, Yuri, since you
are such an unsung genius of electromagnetic analysis, here's a
challenge: design a loading coil for a short vertical radiator that
doesn't have, or has only very little, current variation along its length.
73,
Tom Donaly, KA6RUH