Coils, why?
 

Why not:

___ ___
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
___| |___|


etc.

A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Regards,
JS

P.S. Excuse the bad ascii graphics ...

Coils, why?
 

On Dec 2, 7:09 pm, John Smith wrote:
Why not:

___ ___
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
___| |___|

etc.

A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Regards,
JS

P.S. Excuse the bad ascii graphics ...

Not a very efficient "coil." Consider what the magnetic fields are
from each wire segment. A flat _spiral_ is sometimes used, e.g. by
etching it into a PCB, though they are generally not as good as
traditional helical or toroidal coils. A stub of transmission line
less than a quarter wave long and shorted at the far end looks
inductive, too, but at HF it's a pretty inefficient way to get
inductance. They're much more useful at UHF and above.

Coils, why?
 

K7ITM wrote:
On Dec 2, 7:09 pm, John Smith wrote:
Why not:

___ ___
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
___| |___|

etc.

A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Regards,
JS

P.S. Excuse the bad ascii graphics ...

Not a very efficient "coil." Consider what the magnetic fields are
from each wire segment. A flat _spiral_ is sometimes used, e.g. by
etching it into a PCB, though they are generally not as good as
traditional helical or toroidal coils. A stub of transmission line
less than a quarter wave long and shorted at the far end looks
inductive, too, but at HF it's a pretty inefficient way to get
inductance. They're much more useful at UHF and above.

Interesting response. The "major efficiency" you are stating is?

1) Inductance per length of conductor?

2) Space required for inductor?

3) Losses?

4) Other?

Regards,
JS

Coils, why?
 

John Smith wrote:
"The "major efficiency" you are stating is?"

Q is the usual statement of inductor efficiency.

Libear loading has its advocates. My edition of John Devoldere, ON4UN`s
"Low-Band DXing" is from 1994. On page 9-36 is Fig 9-46, Two-Band (80
and 160-m) vertical system using linear loading to bring the antenna to
resonance on 160 meters.

Best regards, Richard Harrison, KB5WZI

Coils, why?
 

Richard Harrison wrote:
John Smith wrote:
"The "major efficiency" you are stating is?"

Q is the usual statement of inductor efficiency.

Libear loading has its advocates. My edition of John Devoldere, ON4UN`s
"Low-Band DXing" is from 1994. On page 9-36 is Fig 9-46, Two-Band (80
and 160-m) vertical system using linear loading to bring the antenna to
resonance on 160 meters.

Best regards, Richard Harrison, KB5WZI


Thanks Richard, I will see if I can locate an issue that old.

Regards,
JS

Coils, why?
 

John Smith wrote:

Poor old W8JI has taken quite a beating, it is best to realize if
mistakes are made, so should it be, we are only human.

However, this individual has prepared some nice pages, he has a nice way
of writing which are easy to logically follow. Newbies, if they stumble
upon his pages, must surely benefit tremendously.

Now, as I have stated, I have no real horse in the particular argument
which dominates this group--I simply wish to recognise his good work and
give him proper credit. If unknowingly slight men of good intentions we
may lose them--NOT a good thing ...

http://www.w8ji.com/loading_inductors.htm

Warm regards to all,
JS

Coils, why?
 

"John Smith" wrote in message
...
Why not:

___ ___
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
___| |___|


etc.

A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Regards,
JS

P.S. Excuse the bad ascii graphics ...

I tried Linear Loading with a 10-meter Mobile antenna - just to try it out.
If I recall, the performance was about the same as a coil-loaded antenna.
The reason I like coils is that they fit nicely inside (or outside) a piece
of PVC pipe, and makes antenna-making easier.

W4PMJ

Coils, why?
 

(Richard Harrison) wrote in news:24417-
:

John Smith wrote:
"The "major efficiency" you are stating is?"

Q is the usual statement of inductor efficiency.

Not to imply that Efficiency=Q.

In very simple terms, in the case of a coil, the inductance is
proportional to the cross sectional area of the coil. A circular coil
uses the least wire and hence the least resistance to achieve that area.
Techniques that increase the conductor length for the same inductance are
likely to produce a lossier (ie less efficient) inductor.


Libear loading has its advocates. My edition of John Devoldere, ON4UN`s
"Low-Band DXing" is from 1994. On page 9-36 is Fig 9-46, Two-Band (80
and 160-m) vertical system using linear loading to bring the antenna to
resonance on 160 meters.

Linear loading does have its advocates. The claims sometimes made
regarding efficiency are perhaps unjustified. My article at
http://www.vk1od.net/cobra/index.htm explores NEC based system models of
the Cobra antenna system (a linear loaded multiband antenna system) and
the loading mechanism is not inherently lossless.

The case of a non-inductive wire wound resistor is an extreme case of
inefficiency as a result of "linear loading". The objective is to arrange
the conductor so that incremental magnetising forces cancel and just the
loss is retained.

Owen

Coils, why?
 

John Smith wrote:
A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Looks like linear loading to me.
--
73, Cecil http://www.w5dxp.com

Coils, why?
 

Cecil Moore wrote:
John Smith wrote:
A "flattened" coil, first time I see one used is Vincents' DLM, anyone?

Looks like linear loading to me.

Hmmm ...

So are the Tune and Load knobs on my linear! :-D

Regards,
JS