On Nov 21, 3:00*pm, JIMMIE wrote:
On Nov 21, 2:00*pm, Art Unwin wrote:



On Nov 21, 10:51*am, Art Unwin wrote:

On Nov 21, 9:52*am, John Smith wrote:

Art Unwin wrote:
...
Seems to me you are recommending the "?slinky" !
Is that correct?
Art

I believe, he is speaking of rotating the flat surfaces of the
conductor(s) 90 degrees to what a "slinkys'" orientation places them at.

In which case, "mondo-capacitive loading to the 'environment'" is also
introduced ... while minimizing capacitive loading between turns.

Regards,
JS

Wouldn't that take more room than a slinky per turn?
His attic is very small!.I think he would be much better placing the
turns as close together as possible
to obtain axial directivity. The only mod required to the slinky is to
ensure the number of right hand turn loop
are equal to the number of left *hand turned loops. Feed could still
be at the center and depending on the amount
of wire used it would radiate like a dipole or axially. What this does
is cancel the lumped loads created in manufacture which
Wim suggests is a problem ie the two supposedly lumped loads will
cancel
*such that you have several wavelengths of wire helix style and no or
repetitive points of none *reactive impedances. He could ofcourse
place
the windings in a vertical direction to obtain an omnidirectional
pattern and utilise the available room to a maximum.
A lot depends on what frequencies he wishes to use as to what form the
radiator becomes.
Best regards
Art

I forgot to mention that a similar type radiator is shown in Antenna
Applications
Reference Guide by Johnson and Jasik with slight modification. This
design was succeeded by the helix antenna
to obtain circular polarization which is now universal with respect to
space communications.
The beauty of this design is the multiplicity of resonant points and
the use of different frequencies.
*The economy of space is some what altered by the need of multi
wavelength of wire because
of slow wave.but then it enables axial directivity. There are many
hams who are delighted by the slinky performance
and they are still sold in huge numbers to the ham community, so it
must be performing!
Art Unwin- Hide quoted text -

- Show quoted text -

Art, where did you get the idea a slinky had "axial directivity" at
40M. I hazard a guess that it was from reading about helix antennas.
The axial radiation is only true if the diameter of the helix is
fairly large, on the order of 1/pi wavelength usually.
This would be a huge antenna if designed for the frequency(40M) that
the OP was asking.
I can see how this misunderstanding led you to your shoebox
antenna.design.

Gee I hope you arent spending good money filing for a patent on that
thing. I understand that can cost a couple of thousand these days.
However it would be interesting to see you get it.

Jimmie

Jimmie
The diameter of the helix and the pitch of the helix is only a couple
of terms that Krauss applied to a helix antenna which is not in
equilibrium.
He also assumed too much when he assigned more gain to a helix that
could be attained by a antenna not in equilibrium which I strongly
suspect is the belief he had in the displacement current. Krauss did a
lot of pioneering work but the passage of time have pointed to many
errors.
If a helix winding wire is less than a couple of wavelengths then the
radiation will be at right angle to the axis. If the wire length is
above two WL preferably 7-10 WL the radiation peak will be axial
regardless of the diameter or helix angle as long as the radiator is
in a state of equiulibrium. the law that I continually state from the
extension of the Gaussian law of statics which I derived. Wind two
inductors with a common wire but wound in opposite directions and view
with MFJ 259 or alternatively review ARRL publications where they show
a fully wound dipole and then start thinking for yourself instead of
jumping to unfounded conclusions. I also read that the reason that the
EH antenna and the cross field antenna does not work as expected
because they were founded in part on the non existant displacement
current b ut I have not followed up on that from first principles so
it is just a statement
Art