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 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

Hi Tom

I downloaded the 4 pages. Yeah, they are a bit difficult to read, but all
the informationis readable. If there is any particular part that interests
you, I can (hopefully) check to see if it is readable here.

I'll be curious to learn the advantage of this antenna.

Jerry

Horizontal omni with gain... was gonna build one for 6m until I
realized how big it was :-)

Made a sketch from Tenth Ed. ARRL antenna book ... gotta love the used
bookstore

http://www.n3ox.net/files/bigwheel_sketch.pdf

All red circles go to one side of the feedline, all blue go to the
other.

Impedance if the antenna is resonant is apparently about 12 ohms,
suggested matching method is to make each element a little bit short so
that it's a bit capacitive at the desired center frequency and then use
a hairpin inductor to match to 50 ohms.

No details on specific lengths in my book here; just says that each
element is "one wavelength" ... If I'm calculating correctly, think
that you want to shorten the elements enough that the natural feedpoint
impedance of the three paralleled elements is about 12-j21 and then use
a hairpin inductor of about +j28 ohms as the shunt across the
feedpoint.

Dan

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

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,
A model I did some years back showed gain very close to a dipole, much
better omni pattern than classic halo/loops and about a dB better gain than
the loops (once you average their gain around the full 360 azimuth).
This from memory.
Dale W4OP

On 7 Dec 2006 20:27:37 -0800, "
wrote:

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.

What average gain did you expect? In case you had in mind that average
gain would be a big positive number, an antenna doesn't create power,
average gain (ie gain averaged over a sphere) MUST be less than 0dB if
it has ANY loss, mustn't it?

Owen
--

"Owen Duffy" wrote in message
...
On 7 Dec 2006 20:27:37 -0800, "
wrote:

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.

What average gain did you expect? In case you had in mind that average
gain would be a big positive number, an antenna doesn't create power,
average gain (ie gain averaged over a sphere) MUST be less than 0dB if
it has ANY loss, mustn't it?

Owen
--

The way to get gain is to stack them (with phasing) in order to put as much
power as
possible into low angle transmission.

I have 4 stacked 2 meter big wheels originally manufactured by Cushcraft.
Best Regards,
Ed, N5EI

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

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
--