"Richard Harrison" wrote in message
...
The antenna signal travels from the transmitter through the coil and
through the stinger until it reaches the tip where it is forced to
reverse course by the open circuit. All the signal which has not been
radiated or lost in waste enroute starts its journey back toward the
transmitter. This reflected energy from the antenna tip is of no help in
determining delay through the loading coil but the ripples it makes,
when it adds and subtracts from the waveform of the forward energy,
makes measurements difficult. .....

Best regards, Richard Harrison, KB5WZI


Which brings me back to my question: How important is the Q and low
resistance of the coil and stinger? The subtracted waveform (current) seems
to show slight increase at the base of coil, which we are trying to
achieve - prolonging the high current portion along the radiator system.

If we had traveling wave situation along the radiator - almost uniform
distribution (need resistive loading at the tip, just like in Cecil's coil
example or Rhombic/Beverage antennas) - how would that affect overall
efficiency?

When Barry, W9UCW did his experiments and measurements, he was surprised
that quality of the loading coil made hardly any difference. Like good
Bugcatcher coil vs. bad Hustler type resonator.

Do we have the case where some power is being lost for the benefit of
stretching the high current portion along the radiator and making up for
losses?
Normally we always try to minimize the resistive or other loses, but seems
that something "fishy" might be going on, or is it insignificant form
practical purposes, but I still believe that when involving more loaded
elements in an array, things add up and become worthy of considering.
(We are talking about quarter wave vertical resonant radiator not the
Goosian soup :-)

73 Yuri, K3BU.us

Yuri Blanarovich wrote:
Which brings me back to my question: How important is the Q and low
resistance of the coil and stinger?

As the loading coil is moved from base-loading to
top-loading, the average net current through the coil
decreases (assuming no top hat loading). The importance
of coil Q is related to how much net average current
is flowing through the coil.

For instance, the net average current through a
hamstick coil is enough to burn your hand even
after the power has been shut off.

I've always had it in the back of my mind to
install a 16'x6' piece of hardware cloth at
12.5 ft above ground above my GMC pickup,
supported by fiberglass poles. I would mount
the loading coil about a foot below the top
hat. I'll bet that would win any 75m mobile
antenna shootout.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
...
For instance, the net average current through a
hamstick coil is enough to burn your hand even
after the power has been shut off.

I've always had it in the back of my mind to
install a 16'x6' piece of hardware cloth at
12.5 ft above ground above my GMC pickup,
supported by fiberglass poles. I would mount
the loading coil about a foot below the top
hat. I'll bet that would win any 75m mobile
antenna shootout.

Cecil:

Have you been designing and setting up antennas out at Area 51, again?

ROFLOL!!!

Regards,
JS

what is average net current? is there a peak net current?

On May 12, 7:17 am, Cecil Moore wrote:
Yuri Blanarovich wrote:
Which brings me back to my question: How important is the Q and low
resistance of the coil and stinger?

As the loading coil is moved from base-loading to
top-loading, the average net current through the coil
decreases (assuming no top hat loading). The importance
of coil Q is related to how much net average current
is flowing through the coil.

For instance, the net average current through a
hamstick coil is enough to burn your hand even
after the power has been shut off.

I've always had it in the back of my mind to
install a 16'x6' piece of hardware cloth at
12.5 ft above ground above my GMC pickup,
supported by fiberglass poles. I would mount
the loading coil about a foot below the top
hat. I'll bet that would win any 75m mobile
antenna shootout.
--
73, Cecil http://www.w5dxp.com

wrote:
what is average net current?

Average net current is the RMS value of the standing-wave
current. Here is a graph of such from Kraus: "Antennas"
for a 1/2WL dipole:

http://www.w5dxp.com/krausdip.jpg

Half of that graph would represent a 1/4WL monopole.
--
73, Cecil http://www.w5dxp.com

Cecil, W5DXP wrote:
"Here is a graph of such from Kraus: "Antennas" for a 1/2WL dipole."

The Fig. 9-6 that Cecil posted is from an older edition of Kraus. In the
new 3rd edition, the same graph is Fig. 14-2 on page 464.

Best regards, Richard Harrison, KB5WZI

i see nothing about average or peak net current there a t the link
i see no differences by value only of maytters of taste.
Is there someone else here who knows how to explain not fact things so
a normal person can understand what this is all about?

On May 12, 9:58 am, Cecil Moore wrote:
wrote:
what is average net current?

Average net current is the RMS value of the standing-wave
current. Here is a graph of such from Kraus: "Antennas"
for a 1/2WL dipole:

http://www.w5dxp.com/krausdip.jpg

Half of that graph would represent a 1/4WL monopole.
--
73, Cecil http://www.w5dxp.com

wrote:
i see nothing about average or peak net current there a t the link
i see no differences by value only of maytters of taste.

Don't worry, Don, many of the gurus on this newsgroup
don't comprehend it either. Maybe when the light dawns
upon them, they will explain it better than I can.
--
73, Cecil http://www.w5dxp.com

strange
if you dont know average andpeak net current and why use it?

On May 12, 4:33 pm, Cecil Moore wrote:
wrote:
i see nothing about average or peak net current there a t the link
i see no differences by value only of maytters of taste.

Don't worry, Don, many of the gurus on this newsgroup
don't comprehend it either. Maybe when the light dawns
upon them, they will explain it better than I can.
--
73, Cecil http://www.w5dxp.com

On May 12, 7:10 am, "Yuri Blanarovich" wrote:


When Barry, W9UCW did his experiments and measurements, he was surprised
that quality of the loading coil made hardly any difference. Like good
Bugcatcher coil vs. bad Hustler type resonator.

Dunno, I don't see too much difference between any of my homebrew
coils, but when I compared any of those to a hustler, there was a
large
noticable difference. The hustler was terrible.. Like a dummy load on
a
stick. But in comparing any of my usual coils, I don't see a large
difference
in any of them, including those with heavy gauge wire, vs those with
thinner gauge wire.
I've found thinner gauge wire is just fine as long as the wires are
not wound
too close together.
If one tried a hustler coil, and a good bugcatcher coil, and saw
little or
no difference, I would think ground loss was severely overshadowing
coil
loss.
The less ground loss, the more apparant will coil loss become.
Of course, the large hustler coils have a fairly well known design
defect,
and I consider them defective units vs a usual mobile loading coil.
Even my cheap homebrew coils are far superior, and I do nothing
special..
I once did a side by side test of my mobile vs a friends using a
hustler
mast and resonator on 75m. No contest.. He was in the noise to many
stations, where I was solid copy to most all.. About a 2 S unit ?
difference
on average.

Do we have the case where some power is being lost for the benefit of
stretching the high current portion along the radiator and making up for
losses?

Sorta.. To an extent anyway...
The peak point being probably around 75% or so of the total height..
Get too carried away, and excess coil loss will start to offset gains
in efficiency from the improved current distribution.
In testing all my coils, antennas, etc, I've found Reg's program
"vertload"
to be fairly accurate. Both in general performance estimates, but also
in the estimates on coil loss vs size of wire, etc.. His program said
thinner
wire should be ok with only slight losses vs thicker wire, with a
proper pitch
and wire spacing, and in real life it seemed to pan out pretty close.
A center load coil, with more turns than a base load, will have more
loss.
But the overall antenna efficiency is greatly improved, so I know
which
line I'll be standing in when I pick which one I want to use. :/
If you use a large enough top hat, you can have a base loading coil,
and
still have good current distribution. But I don't use hats on
mobiles..
#1, pretty freaking ugly.. #2, I'll kill them on tree branches fairly
quick..
#3, too much wind load at highway speeds.. Tend to flop and whip about
with my flexible fibreglass "masts"..
I use a center loading coil and a fairly long whip as a decent
compromise.
In the driving mode, I have 5 ft under the coil, and 5 ft above it..
In the parked mode, I have 8 ft under the coil, and 5 ft over it by
adding an
extra 3 ft hustler mast at the base.
If thats on one of my trucks, my coil is higher than many peoples
total
antenna height.. At this date, I'm still too chicken to drill a
hole in my
latest car, which is a 2005 corolla... The bad part is thats the one
I
drive most of the time lately...
My honda accord is radioactive, as are both of my trucks, but the
trucks
burn too much gas, and the accord needs some work.. It doesn't get as
good a mpg as the corolla either, although both weigh about the same.
I'm lucky to get 30 on the road in the accord, where the corolla gets
about 37-40 depending on speed..
But I miss not having a radio on the road at night... I've already
been to
my lake property up in OK. four times in that car since I got it..
"905 mile round trip" I've put about 8k on that car already, and have
had
it maybe 3 months or so...
The last was a couple of weeks ago. I did install a 80 and 40 single
coax fed
dipole rig up there last time, so at least the property is radioactive
even if my
car isn't.. That helps...
I strung it up in an old oak tree, and left the coax rolled up by the
tree.
When I pull up, the coax is long enough to reach about anywhere I'd
have
the radio, including in the car. I'll probably add 160m legs later..
MK