On 2/29/2016 2:29 PM, jimlux wrote:
So, if you had a 5-10 meter tall radiator, being used on 80m or 160m,
there's not a lot to be gained by going longer than 15-20 meters for the
radials.
This often heard concept makes intuitive sense. Kind of
like how the roots of a tree should be of a length related
to the tree height or width.
However, it simply isn't true. Actually, the opposite
is true. Jerry Sevick, W2FMI, wrote an article for QST
a long time ago that famously had a photo of a 40 meter
vertical that was something like 7 feet high, with a top
hat, but worked over a huge radial field. The thing
that was funny about the photo was that the antenna was
made of a clothes dryer with metal arms that served as
the top hat and the pole was the radiator. The concept
was that the less you have in the air, the more you need
on the ground. Jerry did seem to know what he was talking
about.
The "capture area" of a short vertical is nearly the same
as that of a 1/4 wave vertical, no matter how small it is
(at least in the absence of losses). Thus there is no
justification for shortchanging it on radials.
Rick N6RK
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