On Dec 2, 12:19 am, "AI4QJ" wrote:
"AI4QJ" wrote in message

The location on the monopole may make a difference. Since a standing wave is
present, the location on the antenna will define the amount of current in
the coil. Mounting near the feedpoint is at a high current point and this
will increase ohmic losses. At approximately the center of the whip, the
current (and ohmic loss) will be minimal. However, more inductance will be
needed in the center location. thus more wire. More wire means more
resistance. In spite of that, many say that the most efficient location is
at near the center of the whip and intuitively I think this generally
correct as long as you use heavy wire.

It does make quite a difference. And this one one part that
bugs me about the taper/delay dilemma.
A coil loaded antenna actually needs more wire than the
comparison 1/4 wave monopole.
I used one of Reg's programs to churn some numbers up.
"Vertload"

The program is metric. I started with a 3m whip, and used a
..3 meter long loading coil, 100 mm diameter, which is close to
four inches. The antenna was tuned for 3.800 mhz, and used
2 ohms as the ground loss.
The coil came out to a 171 turns per meter, or a .17 dia/pitch
ratio.
This first example gave the total height of 3.3m tall overall,
and the coil was at .01m from the base, and the stinger
above the .3m long coil was 2.990m tall. I used 3m of
whip regardless of the coil height.
The base load version needed 51 turns of coil, which
was 16.31 m of wire plus the 3m of the whip. 19.31 m
of wire total. The efficiency was appx 14.49% vs the 1/4 wave.
Then I tried a center load.
To keep the same turn ratio, I had to use a longer coil.
..44m vs the .3m of the base load. Needed 75 turns,
with a coil wire length of 23.92m. 26.92m total wire with the
whip. The efficiency was 24.89 %.
Then I tried an appx 2/3 coil level with 2m base whip,
and 1m stinger. Again, to use the same coil stock,
you would have to lengthen the coil to .53m vs the .3m of
the base load. Would need 90 turns, with a wire length
of 28.69m. 31.69m total wire length with the whip.
The efficiency was 28.02 %.

You actually need more wire than the equal 1/4 wave whip.
Say a monopole at 3.8 mhz is 61.57 ft tall.
The appx 9.84 ft whip base loaded needs 63.35 ft of wire.
The center load needs 88.32 ft of wire.
The 2/3 load needs 103.97 ft of wire.
But it's the still most efficient of the three assuming
no overly high coil resistance.

To me, the coil current taper/delay, etc issue is basically
a non issue. It doesn't really matter to me one way or
the other as the design of the antennas will not change
a whit. Of course, it's nice to know exactly how it
happens, but it's not going to change the design
of the short verticals as far as coil placement, etc.
The optimum locations for those are already well
known, and will not be effected no matter how
thick the lather is whipped up on this NG.. :/
BTW, the optimum coil locations match the
"lumped" theory so close as to make me wonder
why anyone wastes so much energy worrying about
it.. But.. That's just me. I have many things to do and
worry about besides radios and antennas. So I choose
what I do worry about with some care.
This "problem" isn't one of them.. lol..
MK