[NLRS] 2M Big Wheel antenna info

[Doug Reed]

The original performance test article from Oct 1961 compared the various 
Big Wheel versions against a mobile turnstile antenna at its normal 
height 20" above the rear deck of a station wagon. The single Wheel was 
at 15' and the stacked bays at 24'. This obviously gave a serious 
advantage to the Wheel antennas. But it was meant to be a comparison 
against a known performer, the turnstile, rather than a dB gain race.

The numbers reported in the article were 5.7dB gain for the single 
Wheel, 6.2dB gain for the double stack, and 8.1dB for the quad stack. 
The quad stack was what the article compared to a small yagi for gain.

The numbers that Donn suggests are probably closer to the actual gain 
compared to a dipole. The QST figures merely show they performed well 
against the competition and give an indication of the gain advantage of 
the stacked Wheels.

To me, the most interesting aspect of the QST gain numbers is that the 
difference between single and double stack is so minor, only .5dB. This 
is where I'd normally expect to see a 2dB gain from stacking, but it 
doesn't appear. Proper stacking gain does appear when going from double 
to quad stacked versions. One clue might be that the first article says 
to offset the two antennas by about 60 degrees so they will fill in the 
dips in the radiation pattern and achieve a more circular pattern. That 
probably would be enough to make the difference.

It is also interesting to read the praises of the double stack as a 
miracle for digging out the weak ones that couldn't be heard on the 
single Wheel or the turnstile. That sort of advantage doesn't seem to be 
shown in the reported gain difference. It does make me want to try a 
double stack at home, and seems to indicate that you'd want your mobile 
antenna as high as practical, allowing for bridges.

When I was searching, several references to CSVHFS 2006 came up and 
seemed to show one Big Wheel tested .8dBd and another at 1.8dBd. But I 
didn't read the web page to confirm that.

I've been interested in the Big Wheel since I first saw the articles 
back in the late 60's. They don't seem particularly difficult to build 
if you have a good supply of tubing and a fixture or pattern to aid in 
bending. Worst case, you can draw the pattern on a large piece of 
cardboard using a string and magic marker, then use a small hand tubing 
bender for the rest.

With all my talk of single stack, double and quad stack, I feel like I 
should order fries to go with it....

73, Doug Reed, N0NAS.

Glen Overby wrote:
> I googled around and the only pictures I found of big wheels looked like a
> 3-leaf clover.  It didn't look bad.  After seeing the claim of '5.5db over a
> halo' (www.dwtulsa.com), I'm interested!
> 
> Glen
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