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Old February 21st 15, 04:18 AM posted to rec.radio.amateur.antenna
[email protected] nm5k@wt.net is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 757
Default Top Band Antennae?

On Friday, February 20, 2015 at 4:16:04 PM UTC-6, wrote:
gareth wrote:
What is the recommended practice these days for Top Band antennae for
restricted spaces?


That kind of depends on what you mean by "restricted spaces", but in
general you put up the tallest radiator you can assuming the ground
in your area is at least half way decent. Unless you are in a high
wind area, it is pretty trivial to get up to around 10 to 15 meters
tall with decent aluminum and no guys.

Many years ago (50?) it was to adapt a mobile area for fised station use.


I assume you meant mobile antenna, which is very short; a radiator that
is 4 meters tall, or about the height of a single story house, will
easily outperform a mobile whip in the same place. In addition, since
a fixed antenna can be made much sturdier, you can have more top loading
than on a mobile which further improves performance.


--
Jim Pennino


You can also use top guy wires as top loading, which can easily
be longer than most conventional capacity hats. As a bonus, they
keep the antenna from blowing down if the wind huffs and puffs and
tries to blow his antenna down.

Also one good thing about large top loading is the much improved
current distribution through the whip, which can let one place the
loading coil at the base, with little degradation of the current
distribution through the whip, being as you are not depending solely
on coil location to improve current distribution.
That allows one to easily get to the coil to change taps, or one can
use a large roller coil as the inductor.
As mentioned, the bandwidth will be pretty narrow, so one really
would want a way to adjust the coil, unless they don't mind being on
the same frequency all the time. I couldn't live like that, being I often
work CW around the bottom of the band, and phone usually between 1870-
1900 khz or so..