Gene Fuller wrote:

Cecil Moore wrote:
Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields,
and Gauss' law. It is doubtful that you will find any technical
description of charge equalization.


On the contrary, my DC circuits book has an example of the
charges on two identical capacitors equalizing when they
are paralleled.

If I cause 10 coulombs of charge to be on a 10 meter long wire, do I not have a
uniform charge distribution of 1 coulomb per meter on the wire, under dc steady
state conditions? Isn't this required for any equipotential surface?

Richard Clark wrote:
Quite true. Its as if a needle has penetrated the equipotential
shells over that 300V span. Streamlines would probably reveal a dead
short to what are in the distance 300V/90aA = 3,333,333 GOhm resistive
paths.

.....and when we picture this stuff correctly everything works. For an
example the cubical quad antenna.

Quads almost always have long insulated spreaders with long leakage
paths that allow directors and the reflector to "float". So, unlike the
typical Yagi, the elements can charge to whatever potential is around
them.

Everything around the floating element is around the same potential as
the element. There is no corona.

The driven element has a path to ground, as most antennas do, so it is
at a different potential than stuff around the element. Unlike a Yagi,
the quad has the advantage of not having very sharp multiple extended
protrusions into the space around its only "grounded" element.

Not only does the only quad element with a connection that keeps it at
earth potential lack extended protrusions, it also does not have the
highest impedance point of the element at the point where corona or
leakage current is likely to form. This means the quad, unlike the
Yagi, does not have a very high impedance point of the antenna
protruding into space around the antenna where any very tiny leakage
discharges with very low current and very high voltage are better
matched to the antenna.

When we don't get all hung up on the very obvious nonsense that a
closed loop is somhow magically quieter than an open element by virtue
of "dc short", or fixated on an odd idea that the particles hitting
the conductor are the actual instant of noise generation, everything
fits.

In conditions where there is corona or the potential for corona, quads
are less susceptable to noise. As a matter of fact the very reason
quads were used in their initial applications was in the moist high
altitude environment of HCJB, and the quad element was used to prevent
errosion of the dipole elements by corona into the moist air!

When we look at this, it is almost laughable the very people claiming
corona can't be the root cause of what is commonly called p-static
noise are often arguing quad or quad like antenna short the noise of
particles striking the antenna to ground, and thus can't have corona.
Or worse yet they argue moisture prevents corona, when the entire
reason the quad was "invented" was to prevent coronal errosion of
dipole elements in the moist air at HCJB.

73 Tom

Cecil Moore wrote:
Gene Fuller wrote:
Cecil Moore wrote:
Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields,
and Gauss' law. It is doubtful that you will find any technical
description of charge equalization.

On the contrary, my DC circuits book has an example of the
charges on two identical capacitors equalizing when they
are paralleled.

Cecil,

My bad.

I forgot that rain drops and antenna wires are identical. The behavior
of two identical capacitors certainly covers all charge transfer phenomena.

8-)

73,
Gene
W4SZ

Dave wrote:
Gene Fuller wrote:

Cecil Moore wrote:
Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields,
and Gauss' law. It is doubtful that you will find any technical
description of charge equalization.


On the contrary, my DC circuits book has an example of the
charges on two identical capacitors equalizing when they
are paralleled.

If I cause 10 coulombs of charge to be on a 10 meter long wire, do I not
have a uniform charge distribution of 1 coulomb per meter on the wire,
under dc steady state conditions? Isn't this required for any
equipotential surface?



Dave,

No. A good conductor in DC conditions will have an equipotential
surface. Charge distribution depends on the shape of the object and the
external environment. The wire you describe will have higher charge
density near its ends.

Electrostatic analysis would be a lot easier if what you suggested was true.

73,
Gene
W4SZ

My previous comments about the charge on each particle of given
diameter which impinges on a grounded antenna wire appears to have put
you on the right track.

But you are now over-complicating matters. KISS.

A succession of random dis-charges constitutes a noise current induced
in an antenna wire.

Now carry on from there. You'll eventually sort it out.
----
Reg.

Dave wrote:
Gene Fuller wrote:

Cecil Moore wrote:
Try looking in any basic physics text. I believe you will find
discussion of electrostatic forces, equipotential surfaces, fields,
and Gauss' law. It is doubtful that you will find any technical
description of charge equalization.



On the contrary, my DC circuits book has an example of the
charges on two identical capacitors equalizing when they
are paralleled.


If I cause 10 coulombs of charge to be on a 10 meter long wire, do I not
have a uniform charge distribution of 1 coulomb per meter on the wire,
under dc steady state conditions? Isn't this required for any
equipotential surface?


Nope.
73,
Tom Donaly, KA6RUH

wrote:

In conditions where there is corona or the potential for corona, quads
are less susceptable to noise.

Quads are also less susceptible to noise from charged particles
because they tend to distribute the charge locally instead of
through the transmission line like a dipole does.

Corona is like being pregnant. It either exists or it doesn't.
Corona is steady-state ionization of the air. Arcing can occur
without corona.

Or worse yet they argue moisture prevents corona, when the entire
reason the quad was "invented" was to prevent coronal errosion of
dipole elements in the moist air at HCJB.

Apples and oranges, Tom. Since nobody has argued that high
humidity prevents corona during transmitting, your statement
is just an unfair obfuscation of the facts. On a clear-sky,
high-humidity day, the high humidity prevents corona on *receiving*
antennas. The antenna at HCJB did *NOT* report any corona problems
during receive.

The antenna at HCJB had corona problems when 10 KW of
power was being supplied by the transmitter. The energy
necessary to cause the corona was coming from the
transmitter, not from the atmosphere.
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:
I forgot that rain drops and antenna wires are identical. The behavior
of two identical capacitors certainly covers all charge transfer phenomena.

You apparently misunderstood what I was saying. I didn't say
the charge on the charged particle and the wire equalized. I
said, after the charge is transferred to a point on the wire
by the particle, the charge on the wire equalizes up and down
the wire.

But I am always ready to learn something new. Given two identical
conductive spheres with unequal charges, please explain the physics
that prohibits those spheres from equalizing their charges
when they are brought into physical contact.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
If I cause 10 coulombs of charge to be on a 10 meter long wire, do I
not have a uniform charge distribution of 1 coulomb per meter on the
wire, under dc steady state conditions? Isn't this required for any
equipotential surface?

Nope.

But that wasn't the correct question. Given two identical dipole
elements connected by a link coupling, does the charge on each
element equalize with the other?
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Gene Fuller wrote:
I forgot that rain drops and antenna wires are identical. The behavior
of two identical capacitors certainly covers all charge transfer
phenomena.

You apparently misunderstood what I was saying. I didn't say
the charge on the charged particle and the wire equalized. I
said, after the charge is transferred to a point on the wire
by the particle, the charge on the wire equalizes up and down
the wire.

I'm sorry, not up and down the single elementary wire, but
between the two identical elements of a link-coupled dipole.

But I am always ready to learn something new. Given two identical
conductive spheres with unequal charges, please explain the physics
that prohibits those spheres from equalizing their charges
when they are brought into physical contact.
--
73, Cecil http://www.qsl.net/w5dxp