Enlarging on this a bit - They are all examples of charging by particles
hitting or coming near something. Whether it's wind blown dust, snow, or ice,
or raindrops, etc. And whether the charge got on the particles by induction,
tribocharging, or other sources.
There's two notorious effects - one is that "the antenna gets a charge" - which
a static dissipation choke/resistor/whatever will fix. Same for open telegraph
or telephone lines. one of the spectacular forms of this is the "glowing
tips" of helicopters in dust storms, but it also occurs on airplane props, etc.
And, of course, charge accumulating on the airplane body. In planes, you
discharge it with sharp points to force corona to form and bleed off the charge
gradually.
The other effect is where *something other than the antenna* gets charged, and
periodically it breaks down with a spark or corona brush, discharging it.
Basically a relaxation oscillator. That's the one that makes the buzz or whine.
Since the spark is wideband, you're hearing it in your receiver as a sort of
discrete noise source. Obviously, nothing you do to your antenna will do
anything about that.
There is an interesting case reported (I'll have to look for it) where there
were two structures that would get charged, and the charge interacted, so that
caused a changing frequency of discharges (since the relative voltage on the
two objects affected the charging rate in the relaxation oscillator, which
changed the rep rate of discharges). You can create something like this
artificially with a Van deGraaff generator and some suitable spheres (to hold
charge) and spark gaps. Or, with a machine that unspools plastic sheeting from
one roll to another (to make precut lengths) - That one was quite impressive,
because the charging current was impressive (milliamps).
I'm not sure how you'd fix this kind - unless you have control over the
structure AND there's a way to dissipate the static in a "non-periodic" way
(i.e. have lots of sharp points, to turn it into a steady hiss of corona - e.g.
christmas tinsel on the sheet rolling machines).
Interestingly enough St. Elmo's fire isn't actually corona from the objects.
It's a bit more complex - what happens is that the object is wet, and the field
builds up creating electrostatic forces that tend to "spray" particles off the
tip. Those particles are charged, often with sufficient charge that the
surface field is > 3MV/m breakdown of air, so it's the particles that are
glowing, not the object. The other thing is that charged water droplets start
to evaporate, so the radius gets smaller, but the charge remains the same, so
the surface field rises, leading to corona at the particle surface. Salt water
works better than fresh. You can set up a demonstration if you have something
like a 50kV DC supply - put a tray of water with a cork or piece of wooden
dowel standing up in the tray that's wet. Put a flat electrode above the cork
(at least an inch or so, you don't want regular breakdown), and connect the
power supply between tray and electrode. Styrofoam cups work well as supports
for the upper tray (which needs a rolled edge so you don't just get corona off
the edge of the tray- I use foam covered by aluminum foil tape for this kind of
thing) In a dark room, you'll see St. Elmo's fire surrounding the top of of
the cork - it's pretty impressive and it "looks different" than regular old
corona. Corona tends to have a sort of branched fuzzyness that is little
leaders coming off discrete points, while St. Elmo's is more of a glowing
cloud. Hard to describe, and I've not been able to get a good picture of it,
but once you see it you'll know they're different.
BTW, there is a theory that dust devils on Mars glow from corona discharge from
the charged dust particles. There is a famous paper by Renno that reports
glowing sand blowing off the tops of dunes at White Sands National Park. I
think there was recently some sound recordings that seem to confirm this, but
it's not imageable with the current sensors.
On Tue, 16 Dec 2025 22:18:12 -0500, <john@kk9a.com> wrote:
I did not think that a static drain would help precipitation static but I was
curious what experiences others have had. It would be nice if it really was
that simple. Below is what w8JI wrote on the subject:
"Despite having grounded antennas and the same rain or precipitation striking
physically identical antennas, the highest antennas are always noisy and the
lowest antennas are always the quietest. This occurs on a variety of antennas
and in a variety of systems. Antennas with grounded elements and antennas with
insulated elements all behave in similar ways. Antennas near the top of towers,
especially those without taller towers nearby, all have severe p-static in
storms. Lower antennas show very little noise under the same conditions, even
though they are being struck by the same particles.
The cause of noise most commonly called p-static or precipitation static is
obviously not from charged particles striking the antenna. While some of this
might occur under some conditions, the overwhelming cause appears to be corona
discharge from protruding points into space around the antennas or antenna
structures. On dark nights with closing storms, I can look at my upper 40-meter
Yagi with binoculars and see a faint
http://en.wikipedia.org/wiki/St._Elmo's_fire from the element tips. This is
similar to what I saw on the VHF antenna that noised-up during foul weather.
Sailors have seen it on salt-water soaked wooden masts, and we are plagued by
it also. We just have not paid enough attention to the evidence and have missed
the real root cause. We consider it particles striking the antenna was nearly
all cases appear to be the simple phenomena known as St. Elmo's fire.
We can't cure precipitation static, but it can be reduced through the following
steps:
• Having something else much taller than the receiving antenna close to the
receiving antenna or lowering antenna height.
• Avoiding sharp points on or near the antenna. Sharp points increase voltage
gradient and increase corona.
• Avoiding protruding elements. Protruding elements increase corona.
As a general rule the following makes little difference:
• Grounded elements
• DC shunt elements on feed lines
• Improving ground systems or grounding"
John KK9A
From: ve6wz@shaw.ca
Sent: Tuesday, December 16, 2025 8:58 PM
To: john@kk9a.com; Jack Brindle
Cc: towertalk@contesting.com
Subject: Re: [TowerTalk] Static Drain Resistor in Arrestor
Jack,
"P-Static" (precipitation static) is a different phenomena that "wind static".
A grounded antenna will NOT prevent P-Static. W8JI is correct.
Wind static can build incredible voltages (I've seen it) and will discharge to
ground. Grounding the element through a choke or high value resistor will
eliminate this. All my antennas must have this.
Precipitation static is a different thing. This is that screeching, buzzing,
even whistling sound that will crescendo and sputter out, only to start again.
Its the noise that when happening will shut you down from operating.
It happens when a storm is approaching or in effect. I hear it all the time
during rainstorms and even snowstorms.
Grounding the elements on your Yagi or verticals make NO difference at all to
this type of static.
I really don't think precipitation static is well understood regarding how it
develops and the exact mechanism that triggers it, but a google search might
give you some background.
Either way, a static drain choke or resistor will NOT eliminate this type of
noise when it happens.
Steve ve6wz
________________________________________
From: TowerTalk on behalf of Jack Brindle via TowerTalk
Sent: Tuesday, December 16, 2025 4:06 PM
To: mailto:john@kk9a.com
Cc: mailto:towertalk@contesting.com
Subject: Re: [TowerTalk] Static Drain Resistor in Arrestor
Yes, it definitely helps with rain static. If W8JI actually stated that
grounding the elements doesn’t help, he was wrong.
It is important to bring both sides to ground, and together, usually through a
large value resistor or RF Choke that will handle the power. Tieing both sides
of a dipole through this to ground provides a path to bleed off the static
charge, thus eliminating rain static (and snow static, etc). As Wes stated,
adding a fairly large resistor across the dipole insulator really helps. Then
timing that to ground through the arrestor finished the job.
73,
Jack, W6FB
> On Dec 16, 2025, at 5:48 PM, mailto:john@kk9a.com wrote:
>
> Does the Morgan coaxal arrestor help with precipitation static or just the
> arc noise? Rain static can be brutal when contesting. I thought mine might
> be related to using OWA designs with insulated elements but W8JI has stated
> that grounded elements make little difference.
>
> John KK9A
>
> Ron WV4P wrote;
>
> My fullsize 4el 40 with cool dry air wil arc several inches from coax tip
> to ground from static. With the Morgan M303 inline... Nothing. This was
> also very apparent on the SDR (Flex) screen from what looked like lightning
> static crashes to.. Nothing. In that respect, they did exactly what they
> claimed.
>
> Ron, WV4P
>
>
> _______________________________________________
>
>
>
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