The only useful purpose served by making a loop antenna from coaxial
cable is to ensure capacitance balance of the loop against ground, so
sharpening its directional nulls and, incidentally of course, to
support the very thin inner conductor which would otherwise collapse
under its own weight.

The outer coaxial conductor has no effect on signal to noise ratio as
perceived by the receiver. S/N ratio depends only on what's contained
in the local field itself.

If there's any difference in S/N ratio due to use of a tuned loop, as
with a magloop, then it is due to the loop's very narrow bandwidth -
not the shield.
----
Reg.

Reg Edwards wrote:
Precipitation static, eg., from highly charged raindrops and fine snow
or fine sand, impinging on the antenna wire, just causes an increase
in receiver white noise level. It can be reduced but not removed by
using a very thickly insulated antenna wire, like the inner conductor
of a coaxial cable complete with its polyethylene jacket.
----
Reg.

I've never seen a case of precitation static occuring that way.

In every single case I've seen, whether on tall buildings, tall towers,
or antenna hear earth, it has always been corona discharges from the
antenna or objects near the antenna.

How do I know this?

1.) I had side by side "insulated" and "unisulated" Beverage antenna
wires that are otherwide identical except for being spaced a few dozen
feet apart, and the antebnna pointed towards my tall towers had precip
static and the others did not. Both were equal in noise despite the
fact they are hit by the same rain or dust.

2.) I have Yagis on towers that are identical, and the LOWER antenna
almost never has precipitation static despite the fact they are hit by
the same rain or dust.

3.) I've had dipoles at various heights, and the lower dipole always
has much less precipitation staic than the high dipole despite the fact
they get the same rain or dust.

4.) The period of the noise has nothing at all to do with the number of
droplets hitting the antenna. It increases in pitch as the charge
gradient between earth and clouds builds, then when lightning flashes
it immediatly stops without time delay.

5.) On tall buildings on dark nights in storms, we could actually hear
the same pitch noise as the repeaters rebroadcast, and walk to the
noise source and actually see the corona.

6.) Antennas in fiberglass radomes were no quieter than bare metal
dipoles on tall buildings.

7.) I even used an electrostatic sprayer to charge droplets and hit an
antenna, and could only simulate noise when the antenna element had a
sharp point and I got near the sharp point...at which time I could see
faint corona.

73 Tom

In article , Roy Lewallen
wrote:

Yes. American antenna salesmen haven't yet gotten as sophisticated as
the British inventors and purveyors of the CFA. But they're learning. Be
patient -- perhaps someday they'll reach that level.


The CFA proponents weren't sophisticated at all. The "inventors" probably
read half of chapter one of an undergraduate electromagnetics textbook but
forgot to read/understand the rest. Another source of embarrassment was
that one of the CFA backers was a university EE professor. Go figure.
Extraordinary claims but no extraordinary proof. BTW, in case you're
interested, the British/Egyptian inventors' U.S. patent number is
5155495. It's patented so it must work... 73s from N4GGO,

John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

Dear Tom:
Your message may one of the most interesting and unexpected that I have
read in a long time. Some comments follow. Please note my extreme
reluctance to engage in anything but a calm exchange of experiences and
opinions. I have no interest in provoking you.

Your experience does not seem to agree with experience at remote, flat,
treeless sites here in Michigan. Please note the qualifiers in the last
sentence. Especially in the UP of Michigan, at certain times of the year,
P-noise is the major factor in limiting radio use.

P-noise is not found on an antenna imbedded in a clump of trees when an
antenna out in the open (many wavelengths from the first antenna) has
P-noise. The follow-on is that since most sites are urban or suburban, few
radio amateurs will experience P-noise.

P-noise is observed when there is no rain nor thunderstorms, but plenty
of wind. This is suggestive of moving charge discharging into the antenna.
Of course, one could define this action as being "corona." Of course, if
one places enough charge on a piece of metal eventually there will be
"corona." Many antennas have a conductive path to earth that makes such an
accumulation of charge unlikely.

There is no doubt that an antenna experiencing P-noise will radiate and
thus noise will be received by nearby antennas. That is why successful
receiving antennas here in the flatland are placed a long distance from
metallic objects.

Most people have never heard P-noise because their site precludes same.

A paper published in August about 1961 (IEEE Vehicular Transactions) is
one of the few references that has been published that deals with means for
reducing P-noise. The article involved a fixed, not mobile, antenna. It
appears that additional work has not been published that deals significantly
with fixed antennas. (Lots of papers exist dealing with aircraft antennas.)

Your #6 is interesting. Unfortunately, there is so much radiation from
what else is on a tall building that it is difficult to sort out where
excess noise is coming from. An antenna inside of a slightly conductive
radome that is placed a long distance from anything that could radiate might
be different.

Your #7 is especially interesting. Our EMC group has on the drawing
board just such experimentation. We will be on the lookout for "end
effects." Your note is a valuable observation.

Regards, Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:
wrote in message
ups.com...

Reg Edwards wrote:
Precipitation static, eg., from highly charged raindrops and fine snow
or fine sand, impinging on the antenna wire, just causes an increase
in receiver white noise level. It can be reduced but not removed by
using a very thickly insulated antenna wire, like the inner conductor
of a coaxial cable complete with its polyethylene jacket.
----
Reg.

I've never seen a case of precitation static occuring that way.

In every single case I've seen, whether on tall buildings, tall towers,
or antenna hear earth, it has always been corona discharges from the
antenna or objects near the antenna.

How do I know this?

1.) I had side by side "insulated" and "unisulated" Beverage antenna
wires that are otherwide identical except for being spaced a few dozen
feet apart, and the antebnna pointed towards my tall towers had precip
static and the others did not. Both were equal in noise despite the
fact they are hit by the same rain or dust.

2.) I have Yagis on towers that are identical, and the LOWER antenna
almost never has precipitation static despite the fact they are hit by
the same rain or dust.

3.) I've had dipoles at various heights, and the lower dipole always
has much less precipitation staic than the high dipole despite the fact
they get the same rain or dust.

4.) The period of the noise has nothing at all to do with the number of
droplets hitting the antenna. It increases in pitch as the charge
gradient between earth and clouds builds, then when lightning flashes
it immediatly stops without time delay.

5.) On tall buildings on dark nights in storms, we could actually hear
the same pitch noise as the repeaters rebroadcast, and walk to the
noise source and actually see the corona.

6.) Antennas in fiberglass radomes were no quieter than bare metal
dipoles on tall buildings.

7.) I even used an electrostatic sprayer to charge droplets and hit an
antenna, and could only simulate noise when the antenna element had a
sharp point and I got near the sharp point...at which time I could see
faint corona.

73 Tom

wrote in message
ups.com...

Reg Edwards wrote:
Precipitation static, eg., from highly charged raindrops and fine
snow
or fine sand, impinging on the antenna wire, just causes an
increase
in receiver white noise level. It can be reduced but not removed
by
using a very thickly insulated antenna wire, like the inner
conductor
of a coaxial cable complete with its polyethylene jacket.
----
Reg.

I've never seen a case of precitation static occuring that way.

In every single case I've seen, whether on tall buildings, tall
towers,
or antenna hear earth, it has always been corona discharges from the
antenna or objects near the antenna.

How do I know this?

1.) I had side by side "insulated" and "unisulated" Beverage antenna
wires that are otherwide identical except for being spaced a few
dozen
feet apart, and the antebnna pointed towards my tall towers had
precip
static and the others did not. Both were equal in noise despite the
fact they are hit by the same rain or dust.

2.) I have Yagis on towers that are identical, and the LOWER antenna
almost never has precipitation static despite the fact they are hit
by
the same rain or dust.

3.) I've had dipoles at various heights, and the lower dipole always
has much less precipitation staic than the high dipole despite the
fact
they get the same rain or dust.

4.) The period of the noise has nothing at all to do with the number
of
droplets hitting the antenna. It increases in pitch as the charge
gradient between earth and clouds builds, then when lightning
flashes
it immediatly stops without time delay.

5.) On tall buildings on dark nights in storms, we could actually
hear
the same pitch noise as the repeaters rebroadcast, and walk to the
noise source and actually see the corona.

6.) Antennas in fiberglass radomes were no quieter than bare metal
dipoles on tall buildings.

7.) I even used an electrostatic sprayer to charge droplets and hit
an
antenna, and could only simulate noise when the antenna element had
a
sharp point and I got near the sharp point...at which time I could
see
faint corona.
========================================
Tom,

The description "precipitate" clearly applies to what is being
precipitated onto the antenna, eg., rain drops, hail-stones, snow
particles, sand particles in a sandstorm, etc.

When charged to a high potential, on impinging on the antenna wire,
the charge on a particle is suddenly released causing a click in the
headphones. A very rapid succession of small random clicks
constitutes white noise.

I, and everybody else in the uK, have experienced rain static dozens
of times, sometimes 10 or 20 dB above S9 on the S-meter. At the start
of a rain storm and when nearing its end, individual clicks can be
heard. As expected, when the clouds are most highly charged, the
noise is most intense when there is thunder about. It can amount to a
roar. It is loudest on the lower HF bands and at MF but that may be
due to the physically larger antennas.

What you have been suffering from is not precipitation or rain static.
You should give it a different name. If you have never experienced
rain static, perhaps you disconnect your antenna when a thunder storm
storm is approaching and before it starts to rain.
----
Reg.

wrote:
Reg Edwards wrote:
Precipitation static, eg., from highly charged raindrops and fine snow
or fine sand, impinging on the antenna wire, just causes an increase
in receiver white noise level. It can be reduced but not removed by
using a very thickly insulated antenna wire, like the inner conductor
of a coaxial cable complete with its polyethylene jacket.

I've never seen a case of precitation static occuring that way.

I experienced that kind of static in Arizona with wind, extremely
low humidity, and bare wire. I've never experienced it in East
Texas.
--
73, Cecil http://www.qsl.net/w5dxp

"Roy Lewallen" wrote in message
...
Yuri Blanarovich wrote:
. . .
Roy, 'splain to him about this 1/8 or so thing. He still dungetit.

Tom understands it, but I see you don't quite have a handle on it yet.

Roy Lewallen, W7EL

So I "don't get it" because I (and others) see the difference in reality,
when electrostatic shield suppresses the local interference. You explain
behavior of E and H field in the vicinity of antenna but that does not apply
to "W8JI shield is the antenna" and "current at both ends of the loading
coil is always the same".

I will stick to my reality handle, rather than joining scientwist's chorus.

73 Yuri, K3BU

Roy Lewallen wrote:

Bill Ogden wrote:
OK, let me display my ignorance once again.

There are many construction articles about ferrite-core antennas for the low
bands. (Not to mention all the ferrite-core antennas in AM receivers.) Are
these not H-field antennas, to a large extent?

Only very locally, and only to a limited extent.

When a signal originates far from an antenna, the response to E and H
fields is in the ratio of about 377 ohms, the impedance of free space.
This is true for *all antennas*. In other words, all antennas have the
same relative E and H response to signals originating far away.

Very close to a small loop antenna, response is greater to an H field
than E field. It does respond to both, however, as all antennas must. As
you get farther away from the antenna, the response to the H field
decreases in relation to the E field response. At around an eighth
wavelength distance from the antenna, the response to E and H fields are
about the same as for a distant source. Beyond about an eighth
wavelength, the response to the H field is actually *less* than the
response to an E field compared to a source at a great distance. The
ratio of E to H field responses then decreases to the distant value as
you get farther from the antenna.

In summary, the antenna responds more strongly to the H field if the
source is within about an eighth of a wavelength from the antenna.
Beyond that, it actually responds more strongly to the E field relative
to the H field than a short dipole or many other antennas -- you could
more properly call it an "E-field antenna" in its response to signals
beyond about an eighth wavelength. The difference in relative E and H
field response among all antennas becomes negligible at great distances;
for antennas which are small in terms of wavelength, the difference
becomes negligible beyond about a wavelength.

Now, suppose you could make a magic antenna which would respond only to
the H field of a signal originating at any distance from the antenna
(which is impossible).

"A system for determining the modulation imposed on
a curl-free magnetic vector potential field.":
http://jnaudin.free.fr/html/tepvppl.htm

Other 'magic' antennae:
http://rugth30.phys.rug.nl/quantummechanics/ab.htm

Robust OP AMP Realization Of Chua's Circuit:
http://citeseer.ist.psu.edu/kennedy92robust.html

What advantage would it have over a real antenna?

I read the main reason was less electrostatic interference
but with less immunity to strong nearby stations. Does
the magnetic field really have less noise than the E-field?

Polarization is also an interesting component.

Remember that the E/H ratio of any signal originating very far away is
377 ohms, regardless of what kind of antenna or source it came from.

I seem to recall this had something to do with the
speed of light not being infinite.


Roy Lewallen, W7EL

Cecil Moore wrote:

wrote:
Reg Edwards wrote:
Precipitation static, eg., from highly charged raindrops and fine snow
or fine sand, impinging on the antenna wire, just causes an increase
in receiver white noise level. It can be reduced but not removed by
using a very thickly insulated antenna wire, like the inner conductor
of a coaxial cable complete with its polyethylene jacket.

I've never seen a case of precitation static occuring that way.

I experienced that kind of static in Arizona with wind, extremely
low humidity, and bare wire. I've never experienced it in East
Texas.

Isn't this the triboelectric effect? I read this was a big problem for
certain newer wireless applications.

Energized TV antennas always feel 'gritty' when I brush my fingers
lightly across them. Why is that? I also get a very mild shock
sometimes, but that gritty electric sandpaper friction is very strange.

Also the indoor TV antenna collects dust and vaporized
cooking oil like there's no tomorrow. Is this like a Tesla coil?

--
73, Cecil http://www.qsl.net/w5dxp

Bill Ogden wrote:
To return to the ferrite rod antenna: Ignoring the directional null
capability (which might be very useful in some real-world circumstances) is
there any advantage to a small ferrite rod antenna over a short wire antenna?

For the 1980's CA 75m mobile antenna shootouts, a ferrite
rod antenna was used for receiving because the local human
bodies had much less of an effect upon it than, for instance,
upon a hamstick antenna. I always assumed it was because a
human body has more of an effect on the E-field than it does
on the H-field.
--
73, Cecil http://www.qsl.net/w5dxp