On Nov 21, 3:50*pm, John Smith wrote:
Art Unwin wrote:
...
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

Art:

The way I "read" him is, he now has a 1m loop, SINGLE TURN (equiv. to
resonating a 8-12+ ft. whip on the hf bands?) able to do 10-30m--with
WHATEVER "matchbox" he is choosing to run ... he is contemplating on
adding a second 1m turn (to add 40m capabilities, apparently) ... are we
on the same page? ... and, loops are NEVER omni-directional! *Well,
other than one constructed to radiate/receive in the plane of the loop
and run in a horizontal plane, would, perhaps, do some type of
omni-horizontal-polarization?--and a 1m at 10-30m, it ain't such an
animal! (well, maybe-kinda-sorta, but I DON'T KNOW! *I would have to get
hands-on-experience before trusting a ventured reply ... any books I
have ever laid hands on are vague on all this ... )

Personally, the only time I have ever used a loop is for AM broadcast
radio and direction finding (fox hunts) in the 10 to 2m bands, and, I
did NOT want omni capabilities! ... well, there may have been one or
two--but so long ago they escape memory ... I never did "like them."

Or, in other words, I am NOT a "loop guru" ... :-(

Anyway, after all that verbiage, the cut-to-the-chase: *"I would think a
slinky and what he has are two 'different species'."

Regards,
JS

I stated Slinky only because I thought that was what Wim was proposing
and then went from there
If the poster now has a loop without a capacitor that is resonant on
40M then a second loop wound
in the opposite direction when added to the other loop. If he is
adding a lumped load in the form
of a capaciter then all bets are off as Maxwell doesn't entertain
lumped loads in his equations.
Art