Reg Edwards wrote:
A pair of radials behave as a continuous dipole fed at its center
via
a single wire. And it radiates.

If the radials are horizontal and radiating, why is
there virtually no horizontally polarized radiation?
--
73, Cecil
======================================
Cec,
Your use of the word "virtually" indicates a weakness in your ideas on
the subject.

The radiation, as small as it may be, is vertically polarised.
----
Reg.

On 11 Jul 2006 02:22:15 -0700, wrote:

There are VERY good reasons everyone settled on four radials, and it
isn't the old wive's tale about making the antenna look good. Four
radials is a reasonable compromise between excessive common mode
problems and tolerable common mode feedline current problems, pattern,
and cost.

I don't think that is a "wive's tale".

From George Brown's (one of the co-inventors of the ground-plane)
book "and part of which I was" the following quote about the ground
plane antenna:

".... In our initial experiments we found that only two horizontal
rods (ground rods) functions just as well as four. Many people from
the Broadcast Sales organization came by to view our test and they
always expressed doubts as to the ability to radiate uniformity when
only two ground rods were used. To quiet them, we used four ground
rods for a while, thus stilling the criticism. When the antenna became
really popular, we did not dare confess to our ruse."

Danny, K6MHE

What's the matter with 3, equi-spaced radials?

Be economical. Save a radial! It looks better too. And there are no
arguments about directionality.
----
Reg.

On Tue, 11 Jul 2006 14:35:34 +0100, "Reg Edwards"
wrote:

What's the matter with 3, equi-spaced radials?

Be economical. Save a radial! It looks better too. And there are no
arguments about directionality.
----
Reg.

Modeling such an arrangement gave no real noticeable difference
between using three or four radials.

Danny, K6MHE

Reg Edwards wrote:
Reg Edwards wrote:

A pair of radials behave as a continuous dipole fed at its center

via

a single wire. And it radiates.

If the radials are horizontal and radiating, why is
there virtually no horizontally polarized radiation?
--
73, Cecil

======================================
Cec,
Your use of the word "virtually" indicates a weakness in your ideas on
the subject.

The radiation, as small as it may be, is vertically polarised.
----
Reg.



Put a number on it, Reg. Besides, you said, yourself, that Cecil
is always right.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:

Tom Donaly wrote:

wrote:

Cecil Moore wrote:

It's pretty easy to understand. Any two radials,
180 degrees apart and high enough, should theoretically
cancel each other's radiation in the far field.


Not true.


How much not true?


-45 DB, i.e. negligibly not true. :-)

That's what I thought. Sometimes, orders of magnitude are
important. Otherwise, people would be worrying about the fact that
they're closer to the center of the Earth in the middle of the
bottom of a flat bottomed hole than they are at the edges.
73,
Tom Donaly, KA6RUH

John Popelish wrote:

Tom Donaly wrote:

How many photons does it take to make a Watt?


1/(Hz*6.63*10^-34).

The lower the frequency the less energy per photon.

That's joules per second, is it?
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:
John Popelish wrote:

Remember, it is Cecil, not me, who demands agreement or eternal verbal
torture.


I don't demand agreement, John, just resolution.

Resolution in who's mind?

I don't demand anything. I just read, occasionally throw out a
thought, and learn what I can. I accept that sometimes I will learn
something that is wrong, but I just keep trying to fit the pieces
together.

wrote:
Cecil Moore wrote:
A free space vertical with horizontal radials in EZNEC
has horizontal radiation more than 40 dB down from the
vertical radiation. That's a high degree of cancellation.

The issue is the horizontal opposing radials only have that degree of
cancellation for perfectly horizontal directions.

That's the issue? Something that no one has ever asserted
otherwise?

You will be able to see your statement isn't true if you place the
antenna in freespace and look at pattern distortion at various
elevation angles. For example, the 2-d plot is skewed 2.11 dB from
being circular at - 45 and +45 degrees elevation. The skewing gets
worse at larger angles from the plane of the radials.

Just ran that test. There was 0.02 dB difference at +45 and -45.

If the radials were REALLY radiating -40dB in all directions as you
wrongly assume, there would NOT be significant FS change in the azimuth
pattern at various elevations.

There is no significant FS change according to EZNEC.

You looked at horizontal radiation, but the horizontal radials peak
radiation is vertically polarized and nearly off the radial's ends.
(Just like in a dipole pattern.)

Unfortunately for that argument, the radiating currents in
a dipole are in phase, i.e. designed for maximum radiation. The
radiating currents in symmetrical radials are 180 degrees
out of phase, i.e. designed for minimum radiation.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
John Popelish wrote:

Tom Donaly wrote:

How many photons does it take to make a Watt?



1/(Hz*6.63*10^-34).

The lower the frequency the less energy per photon.


That's joules per second, is it?

A watt is a joule per second. The formula gives the number of photons
per second that carry a watt (or a joule per second) once you provide
the Hz (frequency).

By the way, I am having second thoughts as to whether or not there
should be a 2*pi factor in there, since most physics formulas deal
with frequency in radians per second, not cycles per second. But the
photon energy formulas usually deal with wavelength, and I have never
seen one that assumes a wavelength is a radian of a cycle, rather that
a full cycle, so, perhaps Hz is the correct unit.

If anyone can clear this up for me, I would appreciate it.