On Sat, 31 Mar 2007 19:24:43 +0000, Rob Atkinson, K5UJ wrote:
>"For verticlal radiators (including slopers), lay out radials if you can
>one or more of any length and configuration. Don't be discouraged if you
>hear that anything less than (take your pick: 25, 50, 120 and such) will
>useless. Baloney,! Try whatever you can --- even none!"
>Perpetuating this sort of "anything works" attitude only leads to more
On the contrary. You have put your interpretation onto the QST author's
statement, and words in his mouth. He did not say "that any number of
radials, even a few is okay." YOU said that. Had I been writing the piece,
I would have placed far more emphasis on their value, but that isn't the
The VAST MAJORITY of hams live on tiny lots where anything approaching a
quarter-wave radial field is a dream, and many of them give up on
installing any sort of ground or radial system because some hams continue
to insist that only an ideal half wave radial field is worth the trouble.
The piece in the ARRL Antenna Book does an excellent job of addressing the
compromises between the THEORETICALLY IDEAL and the "I can pull this off in
my back yard."
Is a half wave field of 120 radials better than 20 eighth wave radials?
Sure. How much better? You would have a hard time convincing me that it's
more than about 5 dB better, even under the worst of soil conditions. Is a
half wave field of 120 radials practical? I've never seen one outside of
the half dozen broadcast stations where I've worked. And I've heard a bunch
of big signals on 80 and 160.
On my postage-stamp sized lot in Chicago, I had next to nothing (a half
dozen radials about 33 ft long, and that fence. Here in CA, I started with
20 70 ft radials, and have been gradually adding more as I have time. As I
add them, the feed point Z drops some more, and the antenna becomes more
stable. No surprise. It probably radiates a bit more power too. That's why
I'm adding more. But I had a lot of fun in Chicago, with next to nothing, I
had more fun here with only the twenty. So what the QST author is saying
is, do the best you can and call CQ.
W4EF works some 160 contests with a wire hoisted by a balloon near the
short of a salt lake. I don't know what he uses for radials, but I'll bet
it isn't 120 half waves. In spite of falling short of that ideal, he still
managed a pretty good signal in Chicago, 2,000 miles away.
I applaud the guys who did the extensive work to compare field strength
with a widely varying number of radials. This is a lot of work, but quite
worthwhile. But it is also a mistake to attempt to interpolate that good
science to ALL conditions of soil.
A purist approach is a wonderful thing, if you can afford it. Most of us
cannot. For at least 25 years, there has been a growing industry of those
who extract large sums of money from audiophiles on the basis of
pseudoscience and a purist approach to the "ideal."
Jim Brown K9YC
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