Rick,
Your new antenna at 140+ feet (4 wl) might well be in a skip null relative
to the available paths at the moment. There are perhaps 2 things tyou
might do to test the hypothesis.
Using a fairly distance ground wave station (point-to-point) with a
sensitive S-meter and a good bit of time, try running patterns every 15
degrees for all three antennas. With point-to-point, the extra height of
the new antenna will give stronger signals, but you should be able to get
a sense of the pattern by knowing what it theoretically looks like and
then using the differences between the forward lobe strength and the side
and rear readings to see if the forward lobe is indeed what you think it
is. Comparing all three antenna patterns as derived from such a test with
each other should give you a second check on whether you interpreted the
first set of readings correctly.
Second, you could, if feasible, remount the antenna about 1/2 wl lower and
check the DX paths available with that setting. I realize that this might
mean a fixed position temporary mounting, so you might have to pick a
promising direction and hope that path reappears in the near future. Then
compare the 3 antennas again to see if the slightly increased elevation
angle changes the relative signal strengths among the three.
The improved backscatter suggests--but only suggests--that you have good
low angle signal strength. The differential in heights among the three
antennas does not permit this evaluation to be more definite.
If anyone has access to the skip heights for recent 10 meter openings to
LU/PY and to VK/ZL, then you might back calculate the required angles and
their likely upper and lower limits. Then you might compare that to what
can be expected more generally from 10 meters during the course of a
continuing cycle (from one of the prop programs) to determine if the
present height will continue to be too high (assuming the other test tell
you that the pattern is as expected and that therefore you skip angle is
too low for current paths). It might or might not be, relative to the
long run of the paths. A good terrain analysis might also tell you
something further abut the likely elevation angles of your first couple of
lobes up the ladder.
Interestingly, not too many years ago, a number of folks would have
instantly responded that I was crazy to think that such an analysis could
be done at all, let alone on a PC. But virtually all of these matters can
be quantified and calculated with available PC software. Punching keys
may be easier than climbing the tower to remount the antenna, but then
they might tell you to do just that. But then, you would have probability
rather than just guesswork on your side.
Don't know if this helps, but hope so.
-73-
LB, W4RNL
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