On Jun 17, 2:02 pm, "Jerry Martes" wrote:
wrote in message

oups.com...



On Jun 17, 12:47 pm, "Jerry Martes" wrote:

I figured 1.8 inches for 1066 MHz. I wanted to build it into a pvc
pipe cap so there isn't much room to work. Also, am I correct to
assume the 1.8 is the total length, including what is stripped back to
make the connection?
Ralph

Hi Ralph

I dont know what your needs are for this Turnstile antenna, so my input
may be of no value. But, a Turnstile can be made to work by feeding
both
dipoles with one feed point. No phasing harness is needed. Make one
dipole a little short so it is capacitive and the other dipole a little
long
so it is inducvtive.

Jerry

The only problem with that is the antenna will still have basically a
dipole
pattern. I assume he is wanting the usual omni pattern with circular
polarization at the higher angles..
But maybe not... You need the phase line if you want a true omni
"turnstile"
pattern.
But saying that , I have used turnstiles with no line.. But usually on
80m..
And it does change the pattern a bit from the original single dipole,
but not
quite the same as using a phase line.
MK

Hi MK

I may have screwed up, but I think that a pair of dipoles on the same
plane, configured like a pair of non-symetrical Vs could be fed with one
feed point to produce a free space cardiod pattern. That would be one
short dipole and one one longer dipole fed in parallel.

Jerry

Jerry


I'm not sure exactly what you mean.. Normally, a turnstile has both
the elements the same length. If you feed two dipoles cut for the
same band, but at different freq's, and feed with a single feedline,
all it will do is effect the SWR plot.. Will look as a "W"..
If you feed a normal turnstile with one line, but no phasing line,
it will act as a normal dipole in one of the 2 plots you could have
from the antenna. In that case, you could feed with two lines,
and switch directions. "dipole pattern each way". You could then
add 90 degrees to one line, and get an omni pattern..
That would give you three choices in plots..
But if you feed with a single line, you must use the phasing line
if you want the omni "turnstile" pattern.
This can be easily modeled using any modeling program..
You set the phasing in the "source" menu..
MK