Jim Lux wrote:
>For folks that haven't seen the charts.
Blue is all 3
Red is bottom two
Green is bottom one
Thanks to W0UN I fixed the syntax of the
link:http://users.vnet.net/btippett/terrain_&_toas.htm
>Are you sure the advantage comes from moving the main lobe, or from
suppressing the signals (and noise) coming other angles. The main lobe
doesn't move a whole lot, being roughly 5 or 6 degrees TOA all the time.
What really changes a lot between configurations is the gain at 10-15
degrees. For instance comparing the blue and red curves, on the main lobe,
you're only seeing a 1 dB change in gain, which is pretty small. However,
the gain at 11 degrees changes by some 6-7 dB, which is pretty substantial,
especially if you're close to the noise floor, or if the guy on the other
end is.
>Likewise, comparing the red and blue curves against the green curve, the
green pattern strongly suppresses signals coming in low (1-2 degrees). The
shape at 5-6 degrees isn't much different than the others, maybe peaking at
7 instead of 5.
>What really changes between the various configurations is how much other
stuff you get, besides the main lobe. Red adds another 5-6 band of TOAs,
Green adds yet another 5-6 degree band. It's more a "beam spoiling" or
"focussing" more than a "beam moving" operation.
VOACAP statistics over an entire Solar Cycle say there
are NO signals from Europe to NC that are higher than 16 degrees,
so I don't care about secondary lobes, nulls, etc above that
area. If I got QRM from local USA stations at higher angles, I
might care, but 99% of the QRM during an European opening is
also from Europe. I also believe the statistics for Solar Cycle
peaks are more skewed to the higher range of the distribution
shown on the plot, which may account for "Bottom 2" or "Bottom
only" being more common than the total Solar Cycle statistics
shown on the plot predict. I keep prodding N6BV for statistics
at solar peaks versus lows but so far Dean has resisted. ;-)
"beam spoiling", "focusing", "beam moving"...whatever you
want to call it...I just choose the combination that allows
me to hear stations best at given times during the opening.
73, Bill W4ZV
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