Noise level between two ant types
 

Noise level between two ant types
 

Tom Donaly wrote:



Grounding might make it worse. Can you see why?
73,
Tom Donaly, KA6RUH

Yes, but I still doubt it is corona.

tom
K0TAR

Noise level between two ant types
 

Tom Donaly wrote:
Ha, ha! Nice joke, Cecil. I'll tell you what: if you can show
that a group of students can tell whether it's raining or not solely
by listening to the static on a radio with an outside antenna, I
might begin to believe part of what you say. Otherwise, all your
talk about carefully selected references is little more than a
pathetically hollow attempt at self justification.

For you to be right, Tom, every raindrop, every dust particle,
and every snowflake in the world must have exactly the same
charge as every antenna in the world. Please get real.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Tom Ring wrote:
It especially shows up in the 300 inches a year lake effect snowfalls in
northern NY. You can hear it on 6 and 2 quite well. These were DC
grounded yagi antennas on all elements, so no corona available here,
thank you.

Also, K1RQG, who is net control of the EMENet on 14345 Sat and Sun
mornings, had it so bad from rain last weekend that he couldn't copy
most of the participants for a few minutes. And in a heavy rainstorm, I
have doubts that it had much to do with corona.

Tom, methinks we are having our legs pulled.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

wrote:
Do we have more lightning, which is caused by a charge difference
between clouds and earth so severe it actually arcs for thousands of
feet, in heavy rain or on clear dry days?

In Arizona, we have the worst precipitation static on clear dry
days without a cloud in sight. You have just made my argument.

Do the leaders and streamers form on clear dry days, or when the
weather is nasty?

If corona requires clouds, you have lost the argument.

I wonder how many people really understand there is a huge potential
difference between the air and earth even on a calm clear day, and
nasty weather can just make it worse.

If it's not enough to cause ionization, it is NOT corona,
by definition. The charge buildup before a corona discharge
is NOT corona. If the charge doesn't result in ionization,
it is not corona.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Tom Donaly wrote:
Grounding might make it worse. Can you see why?

Quoting the 2000 ARRL Handbook: "Electrical fields under
thunderstorms are sufficient to place many objects such
as trees, hair, and antennas, into corona discharge."

Of course, corona discharge exists and grounding an antenna
might make it worse. But corona discharge is not all that
exists.

And in the absence of clouds, corona discharge is not
likely to exist. Some other mechanism is obviously
responsible for clear-sky charged-particle static.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

wrote:
The earth is one terminal, the air and things in the air (like clouds)
have a charge difference.

But that charge difference is NOT corona unless ionization occurs.
If the charge difference doesn't reach the ionization threshold,
it's not corona, by definition.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Are there any measures of voltage, current, joules or cole
slaw on antennas in this area? Do they experience the "noise"?
Couldn't one connect a large capacitor circuit to store the charge
and
trickle it to a battery?
==========================================

About 20 years ago I measured the charge produced on a 150-feet,
long-wire, end-fed inverted-L antenna, using a DC, 0 to 50 micro-amp,
moving coil meter.

It was a warm afternoon. Temperature about 25 degrees C. There was a
clear-blue, cloudless sky with a dry breeze. I assume very low
atmospheric humidity otherwise the charge would leaked away over the
antenna's insulators.

There was a 300pF receiving-type, air-spaced tuning capacitor in
series with the antenna. The other side of the capacitor was grounded
via the transceiver which was not switched on.

Every few seconds the capacitor was breaking down with an audible
click. I could not see a spark. The plates were spaced about 1mm
apart. It was the clicks which drew my attention to what was going
on. The clicks slowly varied at a rate of 1 every few seconds to as
many as 5 or 6 per second.

I removed the capacitor and grounded the antenna through the
micro-ammeter. The current varied around 10 to 20 microamps. After 5
or 10 minutes the effect gradually died away.

I can't remember the current polarity. The transceiver had not been
damaged.

While making the connections with un-insulated aligator clips I
received one or two mild shocks. All for the sake of science!

Later on in the day, clouds built up and there was a thunder and rain
storm. Electricity had been in the air all along. How it got there I
can't imagine except that it may have been due to the friction of dry
air blowing past the antenna wire.

There was no precipitation unless it was plant pollen in the air. I
don't suffer from hay fever or asthma.
----
Reg, G4FGQ

Noise level between two ant types
 

Reg Edwards wrote:
There was no precipitation unless it was plant pollen in the air. I
don't suffer from hay fever or asthma.

Some 19th century doctors scoffed at the idea that there
could be germs so small that they could see them. :-)
Dust particles come in all sizes. Run some clear air
through a HEPA (High Efficiency Particulate Air) filter
and see what you get.

There are always particles in the air. Sometimes they
carry a charge. Air itself, is made up of particles.
Quantum Electrodynamics tells us that charge transfer is
impossible without particles.

For Tom^2 to be correct, every dust particle that touches
every antenna would have to carry the same identical charge
as the antenna to keep charge from transferring. I would
sure like to see them prove that assertion.
--
73, Cecil http://www.qsl.net/w5dxp

Noise level between two ant types
 

Tom Ring wrote:
The earth is one terminal, the air and things in the air (like clouds)
have a charge difference.


So this is an inverse form of corona? Where it comes from the
surrounding charged air and particles (whatever type they are)? Because
it's not the form I'm familiar with where the end of the antenna has a
high voltage on it.

I don't understand that Tom.

What is "inverse corona"?

Corona comes from a charge difference between two things. In this case
it is NOT a charge difference between the earth and the antenna that
you could eliminate by shorting the antenna to the earth, it is a
difference between the air around the antenna and the earth and things
connected to earth. The corona is leaping off into space around the
antenna, not back towards earth. Tying it to earth will only make it
worse, not better.

I am genuinely asking a question here. If this is the way that noise
occurs, I'd like to know the physical method involved.

In every case I have looked at, and I have looked at dozens very
carefully, it has been corna off the elements. That corna (and the
resulting noise) occurs when there are particles, when there aren't,
and at a rate different than the rate of particles hitting the antenna.

It occurs with radomes and insulated elements and without, it occurs
with grounded elements and without.

It increases with increasing height, especially compared to surrounding
objects. It is worse with protruding sharp points on the elements.

It is worse when the charge difference between earth and sky is
greatest, and less when the charge difference is less. It is terrible
when lightning is almost ready to strike. It often vanishes totally for
a brief period after a ground to cloud lightning strike.

Of course a book, especially a handbook, might say it is something
else. But then what they say should fit what occurs most of the time if
what they say is mostly true.

In my experience, and I probably have much more than most people with
this after changing dozens of antennas to try to eliminate this
problem, the idea the noise comes from an element "charging" or from
particles hitting the antenna is largely incorrect.

I think that idea comes from reading and believing wive's tales and
rumors, and not thinking and experimenting for oneself.

73 Tom