[Towertalk] Re: [CQ-Contest] 4-square vs 40-2CD

[Milt Jensen at N5IA]

Keep 'em both, Dick.  There are never enough antennas!  You will find the
4-Square extremely advantageous in the heat of battle and it will perform
better than the 2 element directional about 30% of the time.

The 4-Square we used at XZ0A in January, 2000 was elevated with 12 radials
on each element and the performance was tremendous.  Same for the 80 Meter
4-Square and the single element 160 Meter Groundplane.

Good luck with your endeavors.

Milt, N5IA

----- Original Message -----
From: "Dick Green" <dick.green@valley.net>
To: "CONTEST" <CQ-Contest@contesting.com>; "Tower"
<towertalk@contesting.com>; "YCCC" <yccc@yccc.org>
Sent: Monday, July 08, 2002 10:51 AM
Subject: [CQ-Contest] 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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