A vertical stack can overcome the path nulls on a wide vertical angle
whose fact is generally more effective than concentrating all the
power on a single antenna of a stated height.
Ten meters are peculiar for two reasons.
The first is the band tendency to work with very low angles, the
second is the relatively easy chance to put an antenna to a number of
WL (even 10 or 20) from ground.
Obviously when a path is covered by only an extremely low angle, the
best is to feed (collect) all the available power into the antenna/s
that produce it. In this case, an horizontal stack would be a good
one, like it happens on VHF.
Just to give a couple of practical "european" examples, although US
west coast is generally a matter of very low angles on 10m, east coast
it's not, expecially with a wide open propagation.
An antenna system which is excellent at 3° but unable to manage angles
in the range of 6-9 degrees is a good insurance of bad results.
On 20m, an antenna at 200ft from ground is often a gap beeing unable
to hear at critical elevations.
To summarize, a stacking system is a good weapon, likewise a yagi
placed at some 10 WL from ground is.
73,
Mauri I4JMY
On Thu, 10 Mar 2005 13:36:39 -0500, Bill Coleman <aa4lr@arrl.net> wrote:
> All these accounts of monstrous antenna arrays are very impressive. My
> question is - are they truly necessary? What is the advantage they
> convey? Does the advantage justify the cost over some smaller array?
>
> At home, I can demonstrate the difference even a small tribander at 15m
> (50 feet) has over a multi-band vertical or a low dipole. Yet when I
> travel to NQ4I's M/M, I don't see as big a difference with his
> excellent antenna farm and my modest tribander. Surely it is there, and
> is reflected in the scores, but it doesn't have as big an impact
> psycologically as you'd think.
>
> During the CQ WW Phone, NQ4I's 10m stations consisted of a three-high
> 5/5/5, with the top rotatable, and the middle steerable between EU and
> JA. The other station had 6/6 to JA, 8/6 to EU with the top steerable
> and a 6 ele fixed on VK/ZL, and another antenna on the carribean /
> south america.
>
> You'd think we'd use the bigger stack to run, right? Actually, the
> second station was far superior. The three-high stack to EU was
> ineffective, but the 2-high stack worked great. In fact, the 8 element
> at 125' was the best antenna of the bunch.
>
> So, isn't one antenna that is just right better than a huge stack of
> mediocre antennas?
>
> Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@arrl.net
> Quote: "Not within a thousand years will man ever fly!"
> -- Wilbur Wright, 1901
>
> _______________________________________________
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> CQ-Contest@contesting.com
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>
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