[NLRS] Anyone using Quads?

[John P. Toscano]

Eric Shook wrote:

> I am interested in finding out if anyone uses Quads
> for their VHF work.  They seem more popular on 6 then
> on the higher bands.  I was looking at a website for
> Lightningbolt quads and it stated that a 2 meter 10
> element Quad offers more gain on a shorter boom then
> some of the larger yagi antennas.

Interesting question and replies so far.

I had been thinking that I might build a cubical quad for 6 meters
to use for roving, with the idea that it would be narrow enough to
be "street legal" -- a 6M yagi at 1/2 wavelength wide is around 3M
or 10 feet, which is a bit much for travelling down the road.  I was
thinking of making it 12 feet long to match the length of the loopers
I'm using for 902/1296/2304.  Some folks get around the highway width
restriction by using a short-boom 3-element yagi mounted at a 90
degree angle to the other antennas, so that the 10-foot width is in
line with the length of the vehicle while in motion, and then rotating
it into line with the other antennas when stopped.

I was also thinking it could be built to be light in weight but pretty
sturdy, so that I could use a fiberglas mast extension in the top of
my existing rover mast when parked, to get the 6M antenna higher up
above ground.  (If you look at my most recent rover configuration,
you can see that the 6M antenna is awfully close to the roof of the
van, which is much closer to the earth than it wants to be for good
radiation.  http://www.tc.umn.edu/~tosca005/2002-09-VHF/index.htm

I've heard some positive reports from a few sources.  A fairly
popular book on Radio Direction Finding recommends using a cubical
quad as one item in your armamentarium.  And of course, there's the
story of KB0LYL who often racks up record numbers of QSO's on 2 meter
FM using a cubical quad antenna.  I also came across a web site that
seems to give this antenna good marks:
  http://autoinfo.smartlink.net/kq6rh/antenna/cubic_qu.htm#Cubic_Quads

But I haven't tried one yet, and haven't found the time to teach
myself how to run a program like NEC to do antenna modelling myself,
no matter how much I would love to do so. . .

A question for Jerry (or anyone else who might know):  why is a quad
so different from something like a loop yagi?  I had heard that going
from a square cross-sectional area to a round one had only minimal
impact on performance, and based on my good luck with loop yagis, I
was surprised to hear the negative comments about quads.  (As Jerry
points out, any basic antenna design can be implemented poorly, as
evidenced by an 11-element yagi whose gain can be nearly doubled by
removing 27% of its elements and re-spacing the remining ones.
Maybe that's the problem with the quads he's examined?)

John (W0JT)