Interesting. But you should really compare them over a longer period,
especially during good spring or fall propagation. In many years of
experience here a full size 4-square with only 4 radials raised about 5'
has performed better than a 40-2cd at 60' on long paths into Russia and
asia. It was sometimes as good as a 40-2cd at 120'. Now that the
40-2cd's are at 90' and 180' it is rarely as good as either one. The
main advantages I see in having both is that the f/b of the 4 square is
better so sometimes it hears better, the takeoff angle is different so
sometimes it is better on some paths, it is good for a quick switch in
direction when getting called by an LU or JA when working Europe, and it
is vertical which provides a choice of polarization(though this doesn't
seem as important as it is on 80m and 160m).
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://www.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> -----Original Message-----
> From: yccc-admin@yccc.org [mailto:yccc-admin@yccc.org] On Behalf Of
Dick
> Green
> Sent: Monday, July 08, 2002 17:51
> To: CONTEST; Tower; YCCC
> Subject: [YCCC] 4-square vs 40-2CD
>
> And the winner is...
>
> I just had the rare opportunity to compare two very different 40m
antennas
> "side-by-side" and thought the results would be of interest. I've had
a
> 40m
> 4-square with 60 buried radials per element for about five years.
> Yesterday,
> I put a used 40-2CD at the top of a 50-foot AB-577/GRC portable guyed
> military surplus mast (HD-73 rotor) and compared the two antennas.
There
> was
> no contest at all: even at 50ft, the 40-2CD is 1-2 S-units louder than
the
> 4-square. Assuming my 1000MP meter is calibrated for 6dB per S-unit,
that
> translates to 6-12dB. I'm sure getting the 40-2CD up higher would
improve
> these results.
>
> I say the opportunity for such a comparison is rare because most
people
> replace one antenna with another rather than keeping the old one and
> adding
> a new one. We often see claims like "this antenna is so much better
than
> my
> old antenna", when the comparison is actually made from memory of what
the
> old antenna was like. That's subjective at best. There's no substitute
for
> being able to switch back and forth under a wide variety of
conditions.
> It's
> also nice when the difference is definitive, as it was in my test.
>
> I've been wondering about the relative merits of the 4-square and beam
for
> some time. A couple of years ago, someone at a YCCC meeting complained
> that
> his 40m 4-square just couldn't keep up with the 2-el beams (can't
remember
> who it was.) I disputed the claim, feeling that my full-size 4-square
with
> 60 radials per element was reasonable close in performance to a 2-el
yagi.
> This assertion was partly based on having done reasonably well on 40m
in
> contests, partly based on denial (building a 4-square is a lot of
work!),
> but mostly based on having misunderstood the theoretical gain numbers
for
> a
> 4-square. I thought that a 4-square had about 5.5dB gain over a
dipole,
> roughly equivalent to a 40-2CD. In fact, the gain of a 4-square is
only
> 5.5dB over a single vertical (monopole.) Near as I can figure it, a
dipole
> over real ground is about 5.5dB louder than a monopole over average
> ground.
> That would make a 4-square about equivalent to a dipole. The 40-2CD
would
> therefore be at least 5.5dB louder than the 4-square, and probably
more if
> the 4-square efficiency isn't optimum. That explains the test results
> pretty
> well.
>
> Before you call me a doofus for making that mistake, go try to find
the
> numbers in the ARRL Antenna Handbook or in ON4UN's Low Band DXing --
the
> numbers are there but you have to do a lot of flipping around and
> converting
> of dBi to dBd, adjusting for ground, etc. A simple table comparing
various
> antenna designs under "typical" conditions would be nice, wouldn't it?
>
> I got really interested in the comparison when I noticed that as my
> contest
> scores got better by improving other antennas, my 40m QSOs always
lagged
> the
> competition. Eventually, it became clear that I was giving away too
much
> on
> 40m and that I must have been wrong about the 4-square. Luckily, the
used
> 40-2CD became available for a one-year loan just as I was pondering
what
> to
> do (the same fellow loaned me an extension kit for the AB-577/GRC that
can
> raise the height to 75 feet.)
>
> Of course, a 4-square has other advantages. If the radial system is
good,
> the radiation angle should be lower. I'll have to check that out on
some
> long-haul paths. More important, the F/B of the 4-square is much
better
> than
> the 40-2CD. The 4-square has an F/B of at least 20dB, while the 40-2CD
> seems
> to be about 5dB-15dB (hard to measure, but it's clearly not very
good.)
> This
> could be important when stateside QRM is bad. Also, the 4-square is
> significantly less noisy than the 40-2CD. Finally, the 4-square can
switch
> directions instantly. Still, all in all, I'll take the extra forward
gain!
> I
> should get a chance to check out the 40-2CD in action this weekend in
> IARU.
>
> I've always loved the "idea" of a 4-square (an antenna you can build
with
> no
> concrete and no help), and it really is an excellent compromise
antenna,
> but
> it just doesn't cut it for bands higher than 80m.
>
> 73, Dick WC1M
>
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