There is a *very large difference* between the pattern of a 2 el 40
yagi at 125 feet and at 92 feet. The (useless?) lobe at 75 degrees on
the 92 foot antenna, raised to 125 feet, drops down to something like
40 degrees with fairly larger gain. I am pulling this figure from
memory. Such a lobe may pick up a higher angle incoming very
effectively. The 92 footer is down substantially at that angle.
Later tonight, I will extend the table I posted up to 140 feet and
show the movement of the upper lobe, as well as the notch between it
and the lower lobe, by 6 foot increments.
I also will try to get AA4NC to post, who has a different experience
with his stacked XM240's, apparently, than some others who have posted
in this thread.
The reason why I am picking the height I am has to do with my using a
single self supporting tower (it's in the woods, and guy wires and
levelling the woods are not an option) with its limited options. More
on this with the extended table.
On Thu, 4 Mar 1999 07:02:49 -0600, John Langdon <email@example.com>
>I have 2 element "shorty" 40M yagis at 65, 125, and 195' with a WX0B
>StackMatch to switch them. Of course, this is from W5 land. The lower
>antenna is better in the afternoon before sunset for listening to signals
>from W1/W2 land which I presume would mimic the high angle path from W1 to
>EU, but often not as good as my 25' high "cloud warmer" dipole I use for
>local skeds in W5. There has never been a time on DX signal at night that
>the 65' antenna was best. Into the Caribbean during contests the 65'
>antenna is very close to the 125, which is better than the 195. On a few
>signals, like VU/4S7 near sunset here, the 195' antenna is better than the
>125, but it is very rare. N3BB is nearby and has a 3 element 40 at 120'
>and that seems to be a sweet spot into EU and JA from here.
>I would recommend the 92' height if it is mechanically feasible.
>73 John N5CQ
Guy L. Olinger
Apex, NC, USA
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