wrote in message
ups.com...
Actually, maybe it doesn't have gain compared to a halo... I'm not
really sure... I have an inconclusive 6m Big Wheel EZNEC model with an
average gain problem... though at this point it's only showing a -0.5dB
average gain or so, and impedance and gain seem constant with
segmentation changes, so it's probably not so bad.

I made it back when I was considering building one and modified it a
little bit to make the avg. gain work out better.

Anyway, if anyone wants to try to get it to work reliably, there's a
model at

http://www.n3ox.net/projects/eznec/6mBigWheel.ez

Dan

Hi Dan

I made a model of two Turnstiles (crossed 1/2 wave dipoles) stacked, one
above the other. EZNEC shows 2.9 dBi gain at the horizon with free space
conditions. The individual dipoles have input impedance of about 68 -J
10.
It seems that two turnstiles, stacked vertically might be a decent choice
for a omniazimuth horizontally polarized 2 meter antenna.

Jerry

What average gain did you expect?

Three megaBels ;-) Seriously, though, most antennas I model end up
being within 0.05dB of zero. You're right about the spacing, I was
making it wide for no particularly good reason ... with the original
segmentation and a more realistic spacing of the transmission-line
wires (0.6 inches or something), I was getting an average gain in free
space with zero wire loss of about -3dB... wider spacing got me closer
to zero.

I was changing the wrong things to fix the average gain discrepancy.
I'll play around with it more as an educational experience... I posted
it mostly because the wire geometry is tricky to get in the first
place, lots of creating loops and deleting segments and so forth, but
it's easy to modify once you've got it, so I figured it would be of
some use.

Now that you've fixed the segmentation, maybe we can put the spacing
back and have a working model... I'll have to look into it.

Thanks Owen..

Dan

I changed your segmentation, W1=1, W8-W43=1, I get average
gain=0.05dB.


I used your segmentation and changed the spacing of the transmission
line sections to both 1 inch and 1.5 inches to be more realistic and
played with the transmission line segmentation and can't get better
than -1dB average gain with zero loss in free space.

What should I do

On 8 Dec 2006 15:08:43 -0800, "
wrote:

....
Now that you've fixed the segmentation, maybe we can put the spacing
back and have a working model... I'll have to look into it.
....

It looks an interesting thing to model.

There are certainly widely ranging claims for its gain in articles on
the 'net.

I have worked up the parameters for a 3D cubic Bezier curve that would
be a good model of half of one of the loops, so I will write some code
to generate a NEC model from it.

Owen
--

Also, was a staple in the ARRL Radio Amateur's
VHF Manual c. 1972 (pgs 198-199) . These were
pretty common in two meter A.M. days, and stacked
pairs worked pretty fair, considering they were
Omni-Directional. Jim NN7K

John Doe wrote:

"Tom Ring" wrote in message
.. .
I've done a fair bit of googling, and haven't found a decent set of plans
to construct a 2m Big Wheel. I have found the original article from 1961,
but the resolution in the pdf is lousy.

Anyone have a link?

tom
K0TAR

I had already checked the index in my oldest ARRL Antenna Book, circa
1974, and nothing in there. Argh.

I sure wish I had a copy of the 1972 VHF Manual. Our Northern Lights RC
monthly breakfast is in about an hour, I'll check there and see if
anyone has that manual. It's a good bet since W0AUS, the blazing core
of our 10 GHz SSB/CW group, has probably been a ham for over 60 years.

Thanks for the tip.

tom
K0TAR

Jim - NN7K wrote:

Also, was a staple in the ARRL Radio Amateur's
VHF Manual c. 1972 (pgs 198-199) . These were
pretty common in two meter A.M. days, and stacked
pairs worked pretty fair, considering they were
Omni-Directional. Jim NN7K

John Doe wrote:


"Tom Ring" wrote in message
.. .

I've done a fair bit of googling, and haven't found a decent set of
plans to construct a 2m Big Wheel. I have found the original article
from 1961, but the resolution in the pdf is lousy.

Anyone have a link?

tom
K0TAR

Tom Ring wrote:
I sure wish I had a copy of the 1972 VHF Manual.

Tom, I've got that one. Big Wheel is on page 198.
What do you need to know?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Tom Ring wrote:

I sure wish I had a copy of the 1972 VHF Manual.


Tom, I've got that one. Big Wheel is on page 198.
What do you need to know?

I'd like a copy of those pages if you could have the ability of scanning
them.

Thanks.

tom
K0TAR

Tom Ring wrote:
I'd like a copy of those pages if you could have the ability of scanning
them.

Is your newsgroup taring.org email address valid?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Tom Ring wrote:

I'd like a copy of those pages if you could have the ability of
scanning them.


Is your newsgroup taring.org email address valid?

Yes, but zip the files them or they won't get here.

Also send me a regular email with no attachments, and I'll give you an
alternate address in case the system eats the zip, too.

tom
K0TAR