Try the old Frank Jones VHF handbook ,he was a "6", (if you can find one)
he did more than a few colinears (includeing an 18 El one for 432) can't
renmember his call, and this NOT modern, (from the 60's) but what you are
essentially trying to do is: from top of element, to bottom of NEXT element,
create a 180 deg phase shift! can do that with a out of (radiation) plane
1/2 wave long (like the center piece of a cushcraft ringo), or RESONATE
CIRCUIT (but, this if high "q" can cause problems, this is also how the
multiple stacked 1/2 wave sections on commet, and many commercial antennas
work! those configured out of stacked , center conductor to shield, and
vice versa coax pieces , all the way to the top, (EXCEPT at the top, they
shorted together, and hit a 1/4 wave rod)! been in handbooks for years--
Jim NN7K


"Tom Bruhns" wrote in message
m...
mike wrote in message
news:c1ac07f922537b76bdd0efbf47136f6b@TeraNews.. .
After much searching (Google and books) I have yet to find an answer.

Does anybody have the formulas for making a phasing coil for collinear
antennas?

I would like to use coils instead of stubs, easier to make enclosures
and mounting points.

Surprised you haven't gotten any other answers on this yet.

Suggest you look for a program that will tell you the self-resonant
frequency of a solenoid coil and use that to _estimate_ the coil you
should use. Try to make some measurements with that and with some
coils a little longer and a little shorter, and also for comparison,
against a measurement of just a simple quarter wave (assume you want
to run it against a ground plane).

Consider also that you could use a coaxial phasing stub: make one of
the elemens from coax whose center shorts to the outer an electrical
quarter wave away from the end; outer is the radiator of that section
and the inner connects to the end of the other section.

But I'd also suggest you read the part of the "Antennas" chapter in
King, Mimno and Wing's "Transmission Lines, Antennas and Waveguides"
that talks about phasing stubs, and suggests that coaxial stubs (and
by implication, phasing coils) do NOT work as well as stubs
perpendicular to the axis of the antenna.

I'm personally partial to the "coaxial collinear" construction in
which transmission line characteristics ensure proper phasing of the
feedpoint voltages between each pair of elements.

Cheers,
Tom