On 15 Nov 2003 11:00:19 -0800, (Art Unwin KB9MZ)
wrote:


|Can you tell me where I can find what the orientation of coil cross
|section does for efficiency ?

Michaels ("Loading Coils for 160-Meter Antennas", QST, April 1990, pp
28-31) might help.

|There are circular cross sections, edge wound cross sections and also
|the ribbon type that Collins uses where the ribbon is coiled on a
|adjacent coil former, why did they choose this method?

I believe the Collins ribbon inductors were designed for variability,
i.e., tunable without any sliding contacts as in roller inductors.

|I am pursuing efficiency, reduction of losses and Collins have a great
|reputation so which form is the state of the art especially with
|corner flux density.
|Another question is that if we split up an inductance into two parts
|does the form factor include the summation of inductances or does the
|distance inbetween
|where coil linkage is not fully formed affect efficiency for the
|worse.
|Discussion like this thread hopefully will enlarge our education to
|see if such things matter . Another question I struggle with is to put
|another element inside the coil where there is max flux density but
|again it can't be resolved by modeling. With the multi antenna experts
|onboard it is always a possibility that a modicom of information will
|be provided that will benefit all.
|As far as inductances, all is not known to my mind and I always would
|like to be privy to more information, and not because I want to build
|a whip

Another interesting reference is Rhea ("Filters and an Oscillator
Using a New Solenoid Model", Applied Microwave & Wireless, November
2000, pp 30-42) In a nutshell, his premise is that the classic
inductor model is in error, particularly with respect interwinding
capacitance.

Some other articles that should be read by all participating in this
thread are by Cebik.

http://www.cebik.com/amod/amod13.html

http://www.cebik.com/amod/amod14.html

Wes Stewart wrote in message . ..
On 15 Nov 2003 11:00:19 -0800, (Art Unwin KB9MZ)
wrote:


|Can you tell me where I can find what the orientation of coil cross
|section does for efficiency ?

Michaels ("Loading Coils for 160-Meter Antennas", QST, April 1990, pp
28-31) might help.

|There are circular cross sections, edge wound cross sections and also
|the ribbon type that Collins uses where the ribbon is coiled on a
|adjacent coil former, why did they choose this method?

I believe the Collins ribbon inductors were designed for variability,
i.e., tunable without any sliding contacts as in roller inductors.

|I am pursuing efficiency, reduction of losses and Collins have a great
|reputation so which form is the state of the art especially with
|corner flux density.
|Another question is that if we split up an inductance into two parts
|does the form factor include the summation of inductances or does the
|distance inbetween
|where coil linkage is not fully formed affect efficiency for the
|worse.
|Discussion like this thread hopefully will enlarge our education to
|see if such things matter . Another question I struggle with is to put
|another element inside the coil where there is max flux density but
|again it can't be resolved by modeling. With the multi antenna experts
|onboard it is always a possibility that a modicom of information will
|be provided that will benefit all.
|As far as inductances, all is not known to my mind and I always would
|like to be privy to more information, and not because I want to build
|a whip

Another interesting reference is Rhea ("Filters and an Oscillator
Using a New Solenoid Model", Applied Microwave & Wireless, November
2000, pp 30-42) In a nutshell, his premise is that the classic
inductor model is in error, particularly with respect interwinding
capacitance.

Some other articles that should be read by all participating in this
thread are by Cebik.

http://www.cebik.com/amod/amod13.html

http://www.cebik.com/amod/amod14.html

Thank you for those references Wes. I really didn't expect to hear
from you again. I now have the computor program to simulate my actual
antenna so efficiency is now of major importance ,I can up my
efficiency to 50 per cent
by hanging a wire down from the dipole ends which I am not comfortable
about
and would rather aproach the coil for loss reduction and go for a beam
setup
by using the radiation efficiently by making it fully directional
stead of figure 8 form
and hopefully I can get those extracts

Reg I tried to enter your page once but I am so computor incompetant.
Looked at a tank circuit today and it was wound flat ribbon form!

Looking forward to looking at this fresh info
Many thanks to both of you
Art

Art, KB9MZ wrote:
"I can up my efficiency to 50 per cent by hanging a wire down from the
dipole ends which I am not comfortable about---."

Why would Art be uncomfortable about improving efficiency by hanging a
wire down?
Maybe he does not believe his model is correct. Maybe he doesn`t want
some directivity change that comes with hanging a wire down. Maybe there
is some physical problem with hanging a wire down.

The problem with a loading coil is increased loss. Capacitance is
usually low loss.

As Yuri, K3BU has noted, there is much to be learned from reading
ON4UN`s Chapter 9 about antenna loading even though everything regarding
vertical antennas doesn`t translate readily to horizontal antennas.

ON4UN includes horizontally polarized antennas in "Low-Band DXing". It`s
easy to read, well illustrated, and full of good references. It helps if
you want to design your own antenna because it tells why as well as how.

Best regards, Richard Harrison, KB5WZI

(Richard Harrison) wrote in message ...
Art, KB9MZ wrote:
"I can up my efficiency to 50 per cent by hanging a wire down from the
dipole ends which I am not comfortable about---."

Why would Art be uncomfortable about improving efficiency by hanging a
wire down?
Maybe he does not believe his model is correct. Maybe he doesn`t want
some directivity change that comes with hanging a wire down. Maybe there
is some physical problem with hanging a wire down.

The problem with a loading coil is increased loss. Capacitance is
usually low loss.

Richard
seem like a sentence got dropped,
What is it that you want to know ?
Are you suggesting using a capacitive coupling instead of
the use of an inductor.........
I think you need to rewrite the post so I can see what your needs are
Regards
Art



As Yuri, K3BU has noted, there is much to be learned from reading
ON4UN`s Chapter 9 about antenna loading even though everything regarding
vertical antennas doesn`t translate readily to horizontal antennas.

ON4UN includes horizontally polarized antennas in "Low-Band DXing". It`s
easy to read, well illustrated, and full of good references. It helps if
you want to design your own antenna because it tells why as well as how.

Best regards, Richard Harrison, KB5WZI

Art, KB9MZ wrote:
"Are you suggesting using a capacitive coupling instead of an inductor?"

The dipole is about the simplest standing wave antenna. Its system must
be resonant to allow full current in the antenna.

The best arrangement for a dipole is a centerfed balanced pair of wires
in a straight line that is self-resonant but this is only possible at
discrete frequencies.

If an antenna is too short to be resonant, it may be resonated by adding
to its inductance or its capacitance, or both, if the antenna can`t be
lengthened.

My remark was only a reiteration of common knowledge. Coils are lossy
and capacitors tend to be nearly lossless.

Cecil has shown how an all-wave system with small losses can be made
that doesn`t even require a tuner. He uses a variety of selected ladder
line lengths to maximize antenna current.

Another option is to use a balanced dipole with a balanced line
connected with the transmitter through a tuner.

Bill Orr, W6SAI has a suggestion for reducing the range of impedances
the tuner must handle. It is to make the sum of the dipole length and
the feedline length into preferred sums. These are 110, 133, 177, or 212
feet. He shows how to make the dipole, balanced line, and tuner in his
book "Wire Antennas". He calls the dipole, line, and tuner: "A Universal
H-F Antenna System", to cover 3.5 to 29.7 MHz with one antenna.

Best regards, Richard Harrison, KB5WZI

Reg I tried to enter your page once but I am so computor incompetant.

----------------------------------------

Art, I'm afraid there's not much hope for you then.

Why not try keeping tropical fish ? It's very relaxing although it can be
livened up by introducing just one pirana to the tank. ;o)
----
Yours, Reg