Hi Mario,
I'm nearly out of time for this, but I'd hate to see anyone sell an
idea that has merit short.
> Obviously, with a radiator that's shorter than 50 ft problems get even
> more evident
While no one can dispute long hat wires near ground are a
problem, we should not neglect comparing a vertical with a sloped
hat to with NO HAT, to see if the hat is a help.
We are after the very best we can do, not perfection in one number.
For example, a 50 foot vertical with 4- 28 foot 45-degree angle hat
wires has an almost identical loop radiation resistance to a 50 foot
center loaded vertical. Before tossing the baby out with the bath
water, it is useful to add the inductor.
When a Q=500 inductor is added the hat vertical has noticeably
higher efficiency, very much larger bandwidth, and uses a
convenient BASE coil location.
The center loaded vertical, even with very slightly more loop
radiation resistance, has less bandwidth, a coil that is hard to
reach, and less efficiency.
So we can say a 50 foot center loaded vertical has about the same
loop radiation resistance as a 50 foot vertical with a hat that comes
down to 30 feet all around the vertical...yet the hat vertical works
better in every possible thing we care about even with a nearly
impossible coil Q of 500! With less Q the difference is
exaggerated more!
If I can get significantly more bandwidth, much more efficiency, and
a more convenient coil location than can use a less difficult to build
coil, I will take all of that even if radiation resistance did not change
enough to make others happy.
The key is always to plan a design, and not make mistakes or poor
assumptions based on only one parameter. But the hat works so
well, I did not even have to plan this for two minutes!
Any vertical you can build without a hat, I can build better with
one.... even if I have to fold the hat down.
73, Tom W8JI
W8JI@contesting.com
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