> Date: Thu, 30 Apr 1998 00:04:41 -0400
> From: "Jim White, K4OJ" <email@example.com>
> In several go rounds on this topic a year or so ago, last I knew:
> W0UN favored grounded elements for noise (static) reasons, if memory
> serves....couple to the element top the boom to the mast and ultimately
> ground so no electrostatic stuff could be on the element......if memory
I'm as puzzled as others (like Cedric?) about all this stuff, and
have been for years and years.
There are a few things that are very well established...
1.) A far field noise signal is no different in ANY electromagnetic
characteristics than a signal from a transmitter or other intentional
radiator. If you look at the far field ratio of electric to magnetic
fields, its exactly the same from a crystal controlled 6L6 rig, a
FT-1000, a lightning strike, or a neon sign. It certainly makes
no difference what the source antenna is, or what you use for
receiving the distant noise (pattern differences excluded).
2.) The near field can be dominated by either magnetic or electric
fields, and whichever induction field dominates is pure
happenstance for that situation.
3.) Static charges do not make noise, only moving charges make noise.
If the charge "moves" at the same rate your receiver passband
accepts, you hear the noise. So a dc grounded element or dc closed
loop makes no difference at all, unless it stops the charge from
One of my best performing 160 meter receiving antennas was an array
of ten foot vertical "e-field" probes in a broadside-endfire phased
array. It made absolutely no detectable difference at all when the
elements were replaced by loop antennas! Nada, zero, zip.
I also did a somewhat unscientific test a few years ago. I connected
a grounded 45-50 kV dc supply hot lead to a garden hose nozzle, and
set it on a PVC stand. I directed a mist of charged water at
different ten meter antennas, and watched the noise. The self-created
precipitation static was no different on a grounded element as a
floating element, as long as I had some kind of leak resistor.
Without the resistor, the corona was a little less but then I would
get big meter pinning pops when the feedline isolation capacitor
Insulated wire, bare wire, it all made no difference at all. The only
thing that changed the corona noise was the addition or removal of a
sharp point at the end of the antenna.
I suspect most of this is just what makes us all feel better about
our antennas, like washing and waxing a car and thinking the
gas mileage went up.
73, Tom W8JI
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