To: <towertalk@contesting.com>
> Date: Sun, 03 May 1998 19:51:11 +0000
> From: David Robbins <k1ttt@berkshire.net>
Hi Dave,
> a rounded object above the antenna would most likely do nothing at
> all. the smooth object would not induce any extra corona that would
> create the charge cloud that would reduce the field strength below
> it.
The mast does reduce the field gradient below and around the mast
without the need for an "ionized cloud".
There are two ways to reduce field gradient. One is by neutralizing
the charge with ions, the other is by distorting or moving the field.
Spraying ions generates noise, and the result is really just that you
create a smooth ball made out of an ion cloud...and noise from audio
to light.... in the process of making the little cloud.
You can find practical examples all over the world that support what
I say. One is on high tension lines, where a round very smooth ring
or ball is used to reduce corona from bolts and other hardware in the
same general area of the line.
Another is in HV systems in TV sets and such. Unavoidable sharp
points are eliminated as corona sources by having blunt points that
extend further towards an opposite charged area, like the chassis.
If you have a sharp point launching a streamer, and add a blunt
conductor that extends past the sharp one and near it, all discharge
will stop....and the noise goes away.
The field distorts and bends away from the antenna quite nicely
without the cloud, and without the electrical noise that could
certainly be made worse by the addition of an intention noise
generator.
73, Tom W8JI
w8ji.tom@MCIONE.com
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|