Plus the simple dipole in your example has a lot less RF coming back into
the shack.
John KK9A
David Gilbert wrote:
There is only a fixed amount of total energy contained in all the lobes
of an antenna. You almost definitely did get lots of lobes ... but you
also got lots of nulls that exactly offset all those lobes. You just
never heard the the hams that were in those nulls and they never heard
you. Whatever you gain in one or more directions is sacrificed in one
one or more other directions. This is basic physics.
More lobes is not necessarily better. In fact, taken to the extreme it
is self defeating because a very large number of lobes (assuming they
were somehow all of equal strength as you stated) begins to approximate
a unidirectional antenna with no azimuth gain in any direction.
Just for grins I modeled your 700 foot antenna in EZNEC+ and on 20m it
gave a maximum gain of about 9 dbi in a fairly narrow lobe at 16 degree
elevation in both directions along the axis of the wire. It also gave a
total of 36 other sharply narrow lobes arrayed symmetrically in all
other directions, each with a gain of about 6 dbi. Between each lobe
was a deep null of around minus 10 dbi. This was all at the same 16
degree elevation angle ... there were literally too many lobes to count
on the 3D pattern, with lots of lobes and nulls at every azimuth and
elevation angle.
A simple dipole at the same 40 foot height would have given similar gain
with a much broader lobe (both azimuth and elevation) in the two main
directions, but of course without the multiple smaller side lobes.
Three poles and two perpendicular dipoles would have given better
overall single band results ... the only advantage of the long wire
being that it gives a similar pattern along with similarly ugly match on
multiple bands.
Dave AB7E
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