Standing waves
 

Frankly speaking no standing waves. Waves always travel. In air travel the
pressure pulse. When the two waves travel in opposite directions they
interfere. See: http://en.wikipedia.org/wiki/Kundt's_tube
"The sound generator is turned on and the piston is adjusted until the sound
from the tube suddenly gets much louder. This indicates that the tube is at
resonance, which means its length is a multiple of the wavelength of the
sound wave. At this point the sound waves in the tube are in the form of
standing waves, and the amplitude of vibrations of air are zero at equally
spaced intervals along the tube, called the nodes."

Between the nodes are places where the amplitude is doubled. So the places
with doubled amplitude are standing. Pressure pulse travel.
In antennas is electron gas. The first place where the doubled amplitude
(amplitude means voltage or electron density) appear is end of the radials.
The next is halve wave apart from the end. Such places radiate strong
electric waves. They are the source of radiation.
Of course the next source is weaker because some part of energy is radiated.
But such is stronger than the trawled source (normal voltage pulse)

If antenna has only one source it is omnidirectional. If two or more is
directional because the waves from different sources interfere.

The halve wave dipole has the two sources. The next two appear than a
dipole is longer than the wave length.
So that what R. Clark wrote is obvious: "[* What is this proportional and
proportionate mean? For a dipole of
0.05 WL to a dipole of 0.5WL, the far field change for that 10:1
variation is negligible. However, for a dipole of 0.5WL to a dipole
of 1.25WL, the far field change for that 2.5:1 (a smaller proportion)
variation is very noticeable.]

The above is the antenna with the Helmholtz' pressure wave.
Could anybody describe the antenna with the Heavisde's TEM waves?
In a few words. Do not send mi to library.
S*

Standing waves
 

On Thu, 17 Sep 2009 19:15:56 +0200, Szczepan Bia?ek
wrote:

If antenna has only one source it is omnidirectional. If two or more is
directional because the waves from different sources interfere.

The halve wave dipole has the two sources. The next two appear than a
dipole is longer than the wave length.
So that what R. Clark wrote is obvious: "[* What is this proportional and
proportionate mean? For a dipole of
0.05 WL to a dipole of 0.5WL, the far field change for that 10:1
variation is negligible. However, for a dipole of 0.5WL to a dipole
of 1.25WL, the far field change for that 2.5:1 (a smaller proportion)
variation is very noticeable.]

In the space of two sentences you contradict yourself. You don't get
it, do you?

73's
Richard Clark, KB7QHC

Standing waves
 

On Sep 17, 10:15*am, Szczepan Bia³ek wrote:
Frankly speaking no standing waves. Waves always travel. In air travel the
pressure pulse. When the two waves travel in opposite directions they
interfere. See:http://en.wikipedia.org/wiki/Kundt's_tube
"The sound generator is turned on and the piston is adjusted until the sound
from the tube suddenly gets much louder. This indicates that the tube is at
resonance, which means its length is a multiple of the wavelength of the
sound wave. At this point the sound waves in the tube are in the form of
standing waves, and the amplitude of vibrations of air are zero at equally
spaced intervals along the tube, called the nodes."

Between the nodes are places where the amplitude is doubled. So the places
with doubled amplitude are standing. Pressure pulse travel.
In antennas is electron gas. The first place where the doubled amplitude
(amplitude means voltage or electron density) appear is end of the radials.
The next is halve wave apart from the end. Such places radiate strong
electric waves. They are the source of radiation.

The problem I immediately see here is that you're probably interested
in electromagnetic radiation, not just the electric field. The
result, as I see it, is that the rest of your discussion is based on a
completely false premise. But see below.
....
The above is the antenna with the Helmholtz' pressure wave.
Could anybody describe the antenna with the Heavisde's TEM waves?
In a few words. Do not send mi to library.
S*

Others have tried to describe radiation from linear antennas in
reasonably simple terms. One of the best I know is Joseph Boyer's
pair of articles from May and June, I think it was, 1978 "Ham Radio"
magazine: "The Antenna-Transmission Line Analog." It's a non-
mathematical work; it will leave you with answers with not a lot to
back them up, but they do match what we observe, as far as I
understand it. I have these as a PDF, along with a fairly important
section from a book referenced by the articles.

Cheers,
Tom

Standing waves
 

On Sep 17, 12:15*pm, Szczepan Bia³ek wrote:
If antenna has only one source it is omnidirectional. If two or more is
directional because the waves from different sources interfere.

More study is needed on your part, S*. Consult the textbooks of the
authors that already have been listed, and quoted here.

Your unproven, personal opinions are not sufficient to support some of
the statements you post-- which accounts for the "negative" comments
responding to them.

Every single real-world antenna in existence has more than one source
along its length that contributes to its radiation pattern, and
therefore has some directionality.

Your study and accurate understanding of the works of the authors
mentioned will prove this.

RF

Standing waves
 

"Richard Clark" wrote
...
On Thu, 17 Sep 2009 19:15:56 +0200, Szczepan Bia?ek
wrote:

If antenna has only one source it is omnidirectional. If two or more is
directional because the waves from different sources interfere.

The halve wave dipole has the two sources. The next two appear than a
dipole is longer than the wave length.
So that what R. Clark wrote is obvious: "[* What is this proportional and
proportionate mean? For a dipole of
0.05 WL to a dipole of 0.5WL, the far field change for that 10:1
variation is negligible. However, for a dipole of 0.5WL to a dipole
of 1.25WL, the far field change for that 2.5:1 (a smaller proportion)
variation is very noticeable.]

In the space of two sentences you contradict yourself. You don't get
it, do you?

"If antenna has only one source" means the monopole antena (the second
source is "graved")
"The halve wave dipole has the two sources" means "dipole has visible the
both ends".
O.K now?
S*

Standing waves
 

"Richard Fry"
...
On Sep 17, 12:15 pm, Szczepan Bia³ek wrote:
If antenna has only one source it is omnidirectional. If two or more is
directional because the waves from different sources interfere.

More study is needed on your part, S*. Consult the textbooks of the
authors that already have been listed, and quoted here.

Your unproven, personal opinions are not sufficient to support some of
the statements you post-- which accounts for the "negative" comments
responding to them.

I wrote: "Do not send me to librery".

Every single real-world antenna in existence has more than one source
along its length that contributes to its radiation pattern, and
therefore has some directionality.

I wrote" "Pressure pulse travel" I means that in monopole antena is one
strong source on the and and traveling source "along its length" .

Your study and accurate understanding of the works of the authors
mentioned will prove this.

Tell me who is right: Helmholtz or Heaviside?
S*

Standing waves
 

On Sep 18, 2:08*am, Szczepan Bia³ek wrote:
I wrote" "Pressure pulse travel" I means that in monopole
antena is one strong source on the and and traveling
source "along its length" .

I assume from what you posted before that you meant to write
"in a monopole antenna there is one strong source on the END..."

Could you please post the reason(s) you think so?

Note that only the change in current and charge, over time,
produces EM radiation. At the top of a monopole, and at the ends
of a dipole the net current is almost zero -- so those locations
generate very little of the total EM radiation from these antennas.

RF

Standing waves
 

Szczepan Bia³ek wrote:
"The halve wave dipole has the two sources" means "dipole has visible
the both ends".

A 1/2WL dipole is a standing wave antenna.
Are you saying that the forward energy is one source
and the energy reflected from the ends is a second
source?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Standing waves
 

K7ITM wrote:
"The Antenna-Transmission Line Analog."

It's a good analog. For instance a 1/4WL open-wire
open-circuit stub made with resistance wire with
a resistivity of 0.0000021 ohms-m has a feedpoint
impedance of 35 ohms according to EZNEC.

The current distribution is a close approximation
to a 1/4WL monopole. The additional resistance
over copper approximates the energy lost to
radiation in a 1/4WL monopole.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Standing waves
 

Richard Fry wrote:
At the top of a monopole, and at the ends
of a dipole the net current is almost zero -- so those locations
generate very little of the total EM radiation from these antennas.

Since the forward current and reflected current are equal
in magnitude and opposite in phase at the ends, they act
like transmission line currents and the magnetic fields
cancel at the ends. They are in phase at the feedpoint -
hence the maximum radiation at that point.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com