It's quite obvious the current through a loading coil tapers. As a first
approximation it's because the voltage and current along it varies according
to a 'cosine' curve as they do along any other sort of continuous
transmission line.

V and I on either side of a coil can be opposite in phase as they pass
through it.

This occurs when the length of the coil passes through a 1/2-wavelength
point. 1/2-wave points can occur at any point along a coil depending on
where the coil starts and ends along the antenna. This helps to illustrate
the action of 'phase-reversing' coils between adjacent antennas lengths.

What I find so intriguing is what the 'taper proponents' intend to do with
the 'taper' data when at last they have it in the form of numbers? Of what
use is it? Into what are the numbers inserted? What is the next stage in
the proposed modelling process?
----
Reg, G4FGQ

What I find so intriguing is what the 'taper proponents' intend to do with
the 'taper' data when at last they have it in the form of numbers? Of what
use is it? Into what are the numbers inserted? What is the next stage in
the proposed modelling process?
----
Reg, G4FGQ



Efiiciency of the loaded radiator is roughly proportional to the area under the
current curve along the radiator.
1. Placement of the loading coil can drastically affect that. (Base loaded vs.
Top Hat loaded)
2. When using loaded elements in multielement designs, the current distribution
and magnitude along the elements needs to be accounted for optimum design and
performance. It affects the inter element coupling, current flow in the
segments of the elements and how the modeling programs "see" it. Try loaded 3
el. 80m beam or 4 square. Programs that can do optimization (YO, AO, 4NEC2)
would give better results if they can deal with real current distribution
closely modeled.
Now it is up to those program authors that neglected proper modeling of the
current in the loading coils to iclude this feature and make their softy wares
better and reflect reality mo betta.

Yuri, K3BU.us

Yuri Blanarovich wrote:
1. Placement of the loading coil can drastically affect that. (Base loaded vs.
Top Hat loaded)

BTW, Yuri, you and others may not be aware that my junk box top-loaded
mobile antenna equaled the best-of-the-best in one of the antenna
shoot-outs. The loading coil was just some cheap 1.75" dia coil stock
from my junk box. It wasn't anything like a bugcatcher and it cost
virtually nothing.

The bottom section was a 108" conductor curving toward the coil which was
***HORIZONTAL***. Yes, the coil was horizontal as was the top hat to which
it was attached. If I had known it was going to do that well, I could have
won by making the top hat a little bigger. Here is an ASCII diagram of that
antenna:
loading coil
- ////////////--Capacitive top hat
/
/
/
/
| Pickup
|
|
|
|
FP
--------GND------------------------------------------------------
So I discovered by accident what is being discussed now. Seems obvious that
the coil could be shorted and the top hat disconnected for higher frequencies.
--
73, Cecil http://www.qsl.net/w5dxp



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Yuri Blanarovich wrote:
1. Placement of the loading coil can drastically affect that. (Base loaded
vs.
Top Hat loaded)

BTW, Yuri, you and others may not be aware that my junk box top-loaded
mobile antenna equaled the best-of-the-best in one of the antenna
shoot-outs. The loading coil was just some cheap 1.75" dia coil stock
from my junk box. It wasn't anything like a bugcatcher and it cost
virtually nothing.


This is what W9UCW measurerd, that Q of the coil did not contribute
significantly to performance. If wire is reasonable gauge to carry the current
to minimize the ohmic loses, then it was very close with that super-duper Hi-Q
coil.

The bottom section was a 108" conductor curving toward the coil which was
***HORIZONTAL***. Yes, the coil was horizontal as was the top hat to which
it was attached. If I had known it was going to do that well, I could have
won by making the top hat a little bigger. Here is an ASCII diagram of that
antenna:
loading coil
- ////////////--Capacitive top hat
/
/
/
/
| Pickup
|
|
|
|
FP
--------GND------------------------------------------------------
So I discovered by accident what is being discussed now. Seems obvious that
the coil could be shorted and the top hat disconnected for higher
frequencies.
--
73, Cecil http://www.qsl.net/w5dxp



That is close to my "secret" K3BU 160m antenna that runs circles around the
"classic" whip. I used 80m regular Hustler coil. From the point where set screw
tightens the whip I run about 13 ft of wire, top loading to small mast on the
front bumper. By sliding that end up and down I managed to tune the antenna
within the bottom end of 160. It also gave me some horizontal component for the
NVIS.
The net result was that even with "lousy" Hustler 80m coil, I managed to
increase the high current carrying portion of radiator, coil didn't have to be
that large, top loading wire also served as a guy. I didn't use real hat, just
wire. Mast is mounted on the fender of 72 Buick LeSabre.
The flat earth society will argue that it can be only 0.1 dB improvement, but I
saw on average about 7 S-units boost. K5NA once travelled with regular 160m
mobile during the contest, didn't make single QSO. With my ugly thing I worked
stations from W6 through South America to Eu.
Another egg in the face Richard and his ridiculing.

73 Yuri

The mobile contacts are impressive,Was the European contacts audio or C.W.,
100 watts? Was you on a beach or something?

Art


"Yuri Blanarovich" wrote in message
...

Yuri Blanarovich wrote:
1. Placement of the loading coil can drastically affect that. (Base
loaded
vs.
Top Hat loaded)

BTW, Yuri, you and others may not be aware that my junk box top-loaded
mobile antenna equaled the best-of-the-best in one of the antenna
shoot-outs. The loading coil was just some cheap 1.75" dia coil stock
from my junk box. It wasn't anything like a bugcatcher and it cost
virtually nothing.


This is what W9UCW measurerd, that Q of the coil did not contribute
significantly to performance. If wire is reasonable gauge to carry the
current
to minimize the ohmic loses, then it was very close with that super-duper
Hi-Q
coil.

The bottom section was a 108" conductor curving toward the coil which was
***HORIZONTAL***. Yes, the coil was horizontal as was the top hat to
which
it was attached. If I had known it was going to do that well, I could
have
won by making the top hat a little bigger. Here is an ASCII diagram of
that
antenna:
loading coil
- ////////////--Capacitive top hat
/
/
/
/
| Pickup
|
|
|
|
FP
--------GND------------------------------------------------------
So I discovered by accident what is being discussed now. Seems obvious
that
the coil could be shorted and the top hat disconnected for higher
frequencies.
--
73, Cecil http://www.qsl.net/w5dxp



That is close to my "secret" K3BU 160m antenna that runs circles around
the
"classic" whip. I used 80m regular Hustler coil. From the point where set
screw
tightens the whip I run about 13 ft of wire, top loading to small mast on
the
front bumper. By sliding that end up and down I managed to tune the
antenna
within the bottom end of 160. It also gave me some horizontal component
for the
NVIS.
The net result was that even with "lousy" Hustler 80m coil, I managed to
increase the high current carrying portion of radiator, coil didn't have
to be
that large, top loading wire also served as a guy. I didn't use real hat,
just
wire. Mast is mounted on the fender of 72 Buick LeSabre.
The flat earth society will argue that it can be only 0.1 dB improvement,
but I
saw on average about 7 S-units boost. K5NA once travelled with regular
160m
mobile during the contest, didn't make single QSO. With my ugly thing I
worked
stations from W6 through South America to Eu.
Another egg in the face Richard and his ridiculing.

73 Yuri

The mobile contacts are impressive,Was the European contacts audio or C.W.,
100 watts? Was you on a beach or something?

Art


They was SSB and CW, some was 100W some was 500W, some was from my driveway,
some was while driving to VE1ZZ place. When close to the ocean or going over
the bridges the signals would jump 10 - 15 dB. Some would say it can't be, but
I say it woz!

73 Yuri, K3BU/m, VE3BMV/m, VE1BY/m
VE3BMV/W4/mm - car submerged in the salt water canal in Miami beach

oUsama (Yuri Blanarovich) wrote in message
The flat earth society will argue that it can be only 0.1 dB improvement, but I saw on average about 7 S-units boost.

Nope. The low 1 db or less figures we tend to harp on is the amount of
modeling error one would likely see. Not related to antenna
improvement by relocating loading coils or addign top loading. I see 2
S units increase on average just from adding the lower 3 ft mast to
mine. "75m" 7 S units is impressive, and fairly believable to me if
the original antenna had a low coil, and no top loading on 160m. That
would tend to indicate you have quite a bit of ground loss to see that
difference. "normal on 160" You have to be real careful when placing
coils and loading wires above sheet metal though. Any sheet metal too
close to the coil or upper whip, and it will totally kill the
performance. I once tried running 2 Vee loading wires from above the
coil, to the front of the car. The antenna was mounted on the trunk
behind the back window. "chevy monte carlo" But it didn't work. The
wires ended up too close to the hood and roof. It might have been ok
if I had a mast on the front of the car to elevate the wires higher
off the car. I sold that car, and now only drive the truck at the
moment. The truck gets the antenna higher overall, but it's more of a
pain because I have an aluminum camper shell on the back. Thats one
reason why I keep the coil well above the roofline...I think it helps
a bit that the antenna is mounted next to a window rather than all
metal.
It only sees a horizontal strip running across, and it's well below
the coil.
I guess your loading wires were far enough away from the body not to
be effected. If it does couple to the body, the antenna will "act"
like it's working, IE: tuning, etc, but will resemble a dummy load
when you try to use it. When I rig up loading wires, I'll run them off
away from the truck to a tree or something. Thats how I currently can
work 160 using my 80-10 antenna. It works fairly well because I'm
using fairly few turns of coil, and a pretty long loading wire. Takes
like 25-30 ft or so if I remember right.
MK

"Yuri Blanarovich" wrote -

Efiiciency of the loaded radiator is roughly proportional to the area
under the
current curve along the radiator.
1. Placement of the loading coil can drastically affect that. (Base loaded
vs.
Top Hat loaded)
=========================

Typically, shifting the loading coil from the bottom of the antenna to its
most efficient location is about 1.5 dB at 7 MHz. Replacing a loading coil
at its most efficient location with a large top hat increases efficiency by
14 percent. Hardly drastic!

But Yuri's objective is not to find the optimum location of the coil along
the antenna. Every twopenny designer knows that THAT point exists.
Especially they who use rules of thumb. And there's nothing wrong with that.

The objective is to assist the coil designer to design coils by telling him
HOW to make use of the EXTRA knowledge of current distribution along the
antenna.

At present, it seems everybody assumes coil current has a uniform
distribution. Nothing wrong with that of course. Especially if everybody
makes the SAME assumption.

It is unwise to use "roughly" and "drastically" in the same context. After
all, it hasn't yet been discovered in which way the taper should go in order
to improve efficiency. (Yes, I know, you can't shift the taper.)

So that how is it proposed to alter the taper. Or to take advantage of it
by altering wire diameter, ie., by putting the lowest wire diameter in the
places where the smallest current flows. And vice-versa.

IF there is success in improving efficiency by, say, 1 percent, as a result
of increasing design and precision engineering costs, plus patenting costs,
plus testing and certification costs, plus manufacturing costs, by 5 or 10
times, would customers be prepared to buy it.

How accurate are (A-B) tests results expected to be? Within limits of
0.01%, 0.1%, 1% or 10% ?

You'll be lucky to obtain an accuracy of antenna power measurements within
+/- 20%, or within +/- 0.8 dB. This means you would be unable to GUARANTEE
to your customers an improvement in performance better (or worse?) than
about +/- 1 dB.

But an improvement of such a relatively large amount, by tinkering with
coils, I venture to say is impossible. So whatever improvement it is
expected to achieve it will be not be possible to honestly demonstrate it.
There is the possibility of an antenna actually being worse than measured.

But the $64,000 Question is whether customers will be prepared to pay for
another 0.5 dB or less gain, which may or may not exist. It would be like
searching for non-existent W.M.D.

On the other hand, it can be confident expected not to measure an antenna
gain worse than about 1 percent of what it actually is. But how do you
assess the difference between two antennas on the basis of back-to-front
ratio over an angle of 360 degrees in the presence of such small
differences.

It is suggested the next questions to ask are "What is the expected change
in improvement" and "How accurately can the expectation be measured".
Economics cannot be avoided.
----
Reg, G4FGQ

Reg Edwards wrote:
It is suggested the next questions to ask are "What is the expected change
in improvement" and "How accurately can the expectation be measured".

Obviously, a sour grapes or sweet lemons situation, depending upon
which side of the argument you are on. Reg, to settle the original
argument, is this statement true?

"If you look at HOW an inductor works, the current flowing in one
terminal ALWAYS equals the current flowing out the other terminal."

A simple "yes" or "no" will settle the original argument and hopefully
end the argument. W8JI's own measurements proved his statement to be
false.
--
73, Cecil http://www.qsl.net/w5dxp



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"Reg Edwards" wrote in message
...
"Yuri Blanarovich" wrote -

Efiiciency of the loaded radiator is roughly proportional to the area
sniped)
=========================

form
distribution. Nothing wrong with that of course. Especially if everybody
makes the SAME assumption.


Reg I really like the above sentence of yours, do you have an English
background
by any chance?

When everybody agrees with an assumption it usually means that the
assumption was
made by a lemming and all the others are followers, knowing full well every
body
cannot be fired, only those who dare to stand alone.
Cheers and beers
Art


----
Reg, G4FGQ