My take on antenna nulls from arrays comes from playing with extra large
Horizontal Loops at Field Day, up to 1200 feet of wire circumference!
Classic modeling shows nulls in the multi lobed patterns of symmetric loops.
However, plotting states and sections worked shows a good fill in in
expected null zones.
Current ionospheric theory says there is not a uniform layer, but clouds of
ionization. It is possible that the reflections from varying ionosphere
tends to fill in the areas of null you would otherwise find.
Or looking at it another way, a station beams his signal away from his area
which is in your null, and it refracts and reflects such as to fall within
your major lobes.
Phasing does work, but on antennas that squirt signal theoretically in
various lobes, the nulls may not be complete from on the air observations.
Either stronger signals over come them, or conditions bend the lobes and
nulls effective directions. Kind of hand waving, but that is what we have
seen over 6 years of careful Field Day attention to large Vee beams, Double
Zepps and horizontal Vees.
73,
Stuart
K5KVH
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