"Richard Clark" wrote in message
...
On Sun, 13 Sep 2009 02:08:20 +0100, "christofire"
wrote:

I had understood it to be impossible on the basis of normal physics but
Art
Unwin's claim wasn't clear in respect of polarisation.

Hi Chris,

Black body radiators do qualify as Isotropic; and as Art has claimed
high efficiencies for RF impracticalities, it must be for efficient
Infrared emission.

73's
Richard Clark, KB7QHC


.... but are randomly polarised, and I'd expect communication between a
randomly-polarised antenna and either a normal, polarised antenna or another
randomly polarised one to be lossy in comparison with the unusual case.

Nevertheless, the principle that heaters are highly efficient is an amusing,
occasionally useful one - standby dissipation contributing to heating your
house and all that.

Chris

"christofire" wrote in message
...

"Richard Clark" wrote in message
...
On Sun, 13 Sep 2009 02:08:20 +0100, "christofire"
wrote:

I had understood it to be impossible on the basis of normal physics but
Art
Unwin's claim wasn't clear in respect of polarisation.

Hi Chris,

Black body radiators do qualify as Isotropic; and as Art has claimed
high efficiencies for RF impracticalities, it must be for efficient
Infrared emission.

73's
Richard Clark, KB7QHC


... but are randomly polarised, and I'd expect communication between a
randomly-polarised antenna and either a normal, polarised antenna or
another randomly polarised one to be lossy in comparison with the unusual
case.

* That was meant to be 'the usual case' - I let the spell checker have its
way without looking at the result!


Nevertheless, the principle that heaters are highly efficient is an
amusing, occasionally useful one - standby dissipation contributing to
heating your house and all that.

Chris

"Szczepan Bia³ek" wrote in message
...

"christofire" wrote
...


Now I understand what you meant by 'total field' - sum of powers of
components in all polarisations.

Does one wave has many polarizations, or one antenna has many
polarizations? Which one: transmitter or receiver? Could you teach me?
A*


You appear to have changed your identity from S* to A* !

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a

A single EM wave is plane polarised. It is composed of a magnetic field H
that acts in a direction perpendicular to the direction of propagation, the
magnitude and sign of this field varying as a travelling wave in the
direction of propagation, and an attendant electric field E that also acts
in a direction perpendicular to the direction of propagation. The magnitude
and sign of the electric field varies as a travelling wave, coherent and in
phase with the magnetic field and the magnetic field is a direct consequence
of current flowing in the transmitting antenna. The directions in which the
H and E fields act, in the plane transverse to the direction of propagation,
are mutually perpendicular and the direction in which the E field acts, by
convention, defines the polarisation.

Thus a single EM wave has a single, plane, polarisation. Different
combinations of waves are possible such as circular polarisation and, more
generally, elliptical polarisation, but these can always be resolved into
orthogonal plane components.

Simple antennas like straight-wire dipoles and loops transmit and respond to
plane polarised EM waves. More complicated antennas can be made to transmit
and receive circular polarisation of one sense or the other, and generally
an antenna will tend to transmit or be sensitive to some combination of
different plane polarisations. In addition to radiated EM waves, there are
also induction fields in a region close to the antenna.

In a system that contains no anisotropic material (e.g. magnetised ferrite),
when the distance between transmitting and receiving antennas is at least
tens of wavelengths, the principle of reciprocity applies. By this
principle the properties of an antenna when transmitting are the same as
when it is receiving - the properties including the polarisation, radiation
pattern and terminal impedance.

If you find any of this interesting, please don't believe what I've written
here but go to a technical library (e.g. at a University) and look up the
authoritative sources - books on antennas and propagation by Kraus, Jasik,
Jordan and Balmain, Terman, etc.

Please _do not_ respond here telling me or the group that EM waves are
longitudinal and are not polarised.

Chris

"christofire" wrote in message
...

"Szczepan Bia³ek" wrote in message
...

"christofire" wrote
...


Now I understand what you meant by 'total field' - sum of powers of
components in all polarisations.

Does one wave has many polarizations, or one antenna has many
polarizations? Which one: transmitter or receiver? Could you teach me?
A*


You appear to have changed your identity from S* to A* !

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a

A single EM wave is plane polarised. It is composed of a magnetic field H
that acts in a direction perpendicular to the direction of propagation,
the magnitude and sign of this field varying as a travelling wave in the
direction of propagation, and an attendant electric field E that also acts
in a direction perpendicular to the direction of propagation. The
magnitude and sign of the electric field varies as a travelling wave,
coherent and in phase with the magnetic field and the magnetic field is a
direct consequence of current flowing in the transmitting antenna. The
directions in which the H and E fields act, in the plane transverse to the
direction of propagation, are mutually perpendicular and the direction in
which the E field acts, by convention, defines the polarisation.

Thus a single EM wave has a single, plane, polarisation. Different
combinations of waves are possible such as circular polarisation and, more
generally, elliptical polarisation, but these can always be resolved into
orthogonal plane components.

Simple antennas like straight-wire dipoles and loops transmit and respond
to plane polarised EM waves. More complicated antennas can be made to
transmit and receive circular polarisation of one sense or the other, and
generally an antenna will tend to transmit or be sensitive to some
combination of different plane polarisations. In addition to radiated EM
waves, there are also induction fields in a region close to the antenna.

In a system that contains no anisotropic material (e.g. magnetised
ferrite), when the distance between transmitting and receiving antennas is
at least tens of wavelengths, the principle of reciprocity applies. By
this principle the properties of an antenna when transmitting are the same
as when it is receiving - the properties including the polarisation,
radiation pattern and terminal impedance.

If you find any of this interesting, please don't believe what I've
written here but go to a technical library (e.g. at a University) and look
up the authoritative sources - books on antennas and propagation by Kraus,
Jasik, Jordan and Balmain, Terman, etc.

Please _do not_ respond here telling me or the group that EM waves are
longitudinal and are not polarised.

Chris


.... but the libraries are probably closed today so, for an instant, online
source you could do worse than visit
http://www.globalsecurity.org/milita...icy/navy/nrtc/, download
the NEETS module 'ELECTRONICS TECHNICIAN, VOLUME 07--ANTENNAS AND WAVE
PROPAGATION ' and read it. It's based on the same, real world physics.

Chris

On Sun, 13 Sep 2009 12:46:30 +0100, "christofire"
wrote:

Does one wave has many polarizations, or one antenna has many
polarizations? Which one: transmitter or receiver? Could you teach me?
A*


You appear to have changed your identity from S* to A* !

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a


A much simpler, and compelling explanation:
what you see is what you get.

If it looks vertical, the polarization is vertical;
If it looks horizontal, the polarization is horizontal.

It thus stands to reason that if the radiator is U shaped you see both
horizontal and vertical - hence the full sphere filled with radiation.

This closes the simple answer, which of course drives a very lengthy
explanation - there is no such thing as a free lunch:

Now, I can well anticipate some wag pointing out that they are
standing, looking at these "goal posts" edge on and see only the
vertical supports. "There is no horizontal view - no horizontal
polarization. It can't be isotropic!"

Of course it can't; and yet the vertical radiation fills the null of
the horizontal (and likewise, the horizontal fills the null of the
vertical). Total field is spherical.

What does this make of a tilted radiator? What you see is what you
get. At some perspectives it looks goofy horizontal AND it looks
goofy vertical. In other perspectives it just looks vertical. As Art
might protest: "Never mind goofy, how much horizontal?" If we reduce
this to a number of goofiness, a trig function would serve quite well.
Most students who were trained in mechanics would recognize the method
to deconstruct an angle into its two, XY, components. If the tilt
were 45 degrees, in full view of that angle you must experience the
single antenna as having two equal vertical and horizontal
contributions to radiation. If it were tilted 30 degrees, obviously
one polarization would dominate over the other. Ground would compound
the issue, but would not negate the general principle.

This last part returns us to the discussion of isotropism which
encompasses the topic of Lambert's Law which is generally confined to
a black body radiator (or the sun from a great distance as it fails to
be isotropic in the near view, such as we have here on earth). Few
here need concern themselves with this unless they are making patch
antennas. However, within the discussion above, the topic of view,
angle, and radiation contribution are wrapped up in Lambert and
cosine.

73's
Richard Clark, KB7QHC

"christofire" wrote
...

"Szczepan Bia³ek" wrote in message
...



You appear to have changed your identity from S* to A* !
Sorry. Mistake (A is adjacent to S).

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a

A single EM wave is plane polarised. It is composed of a magnetic field H
that acts in a direction perpendicular to the direction of propagation,
the magnitude and sign of this field varying as a travelling wave in the
direction of propagation, and an attendant electric field E that also acts
in a direction perpendicular to the direction of propagation. The
magnitude and sign of the electric field varies as a travelling wave,
coherent and in phase with the magnetic field and the magnetic field is a
direct consequence of current flowing in the transmitting antenna.

But there is the second direct consequence. If the current oscilate at the
ends is developed the very high voltage. The high voltage produce the
electric field. So you can wrote: "the electric field is a direct
consequence of voltage developed in the ends of the transmitting antenna".
This electric field generate the magnetic field and so on. So the Hertz'
dipole has the three sources of waves. The centre and the two ends.
It seams that waves from the centre are mainly transverse and that from the
ends mainly longitudinal.
Long wire antennas have many sources. Directional patern is number source
dependent.

You do not like the word voltage. May be the better is polarity.

R. Clark wrote: "Actually you have mixed up two different characteristics.
Polarity
and polarization are NOT the same thing. With RF radiation, the wave
is constantly changing polarity (that is why the source of RF is
called alternating current), but within the "line of sight" of the
antenna, the polarization for a dipole is defined by its angle to the
earth as viewed by the observer.

If you see an horizontal dipole, it produces alternating polarities of
waves with horizontal polarization. If you see a vertical dipole, it
produces alternating polarities of waves with vertical polarization."


The directions in which the
H and E fields act, in the plane transverse to the direction of
propagation, are mutually perpendicular and the direction in which the E
field acts, by convention, defines the polarisation.

Thus a single EM wave has a single, plane, polarisation. Different
combinations of waves are possible such as circular polarisation and, more
generally, elliptical polarisation, but these can always be resolved into
orthogonal plane components.

Simple antennas like straight-wire dipoles and loops transmit and respond
to plane polarised EM waves. More complicated antennas can be made to
transmit and receive circular polarisation of one sense or the other, and
generally an antenna will tend to transmit or be sensitive to some
combination of different plane polarisations. In addition to radiated EM
waves, there are also induction fields in a region close to the antenna.

In a system that contains no anisotropic material (e.g. magnetised
ferrite), when the distance between transmitting and receiving antennas is
at least tens of wavelengths, the principle of reciprocity applies. By
this principle the properties of an antenna when transmitting are the same
as when it is receiving - the properties including the polarisation,
radiation pattern and terminal impedance.

If you find any of this interesting, please don't believe what I've
written here but go to a technical library (e.g. at a University) and look
up the authoritative sources - books on antennas and propagation by Kraus,
Jasik, Jordan and Balmain, Terman, etc.

Do they use the vord voltage?

Please _do not_ respond here telling me or the group that EM waves are
longitudinal and are not polarised.

EM waves by Heaviside are transverse. Now we should check if he was right.
S*

On Sun, 13 Sep 2009 19:57:22 +0200, Szczepan Bia?ek
wrote:

EM waves by Heaviside are transverse. Now we should check if he was right.

You have confused the telegrapher's equations with propagation.

Before you recite an authority, you really need to understand them.

73's
Richard Clark, KB7QHC

"Szczepan Bia³ek" wrote in message
...

"christofire" wrote
...

"Szczepan Bia³ek" wrote in message
...



You appear to have changed your identity from S* to A* !
Sorry. Mistake (A is adjacent to S).

The answers according to the physics that real-life radio communication
depends upon, and was designed by, a

A single EM wave is plane polarised. It is composed of a magnetic field
H that acts in a direction perpendicular to the direction of propagation,
the magnitude and sign of this field varying as a travelling wave in the
direction of propagation, and an attendant electric field E that also
acts in a direction perpendicular to the direction of propagation. The
magnitude and sign of the electric field varies as a travelling wave,
coherent and in phase with the magnetic field and the magnetic field is a
direct consequence of current flowing in the transmitting antenna.

But there is the second direct consequence. If the current oscilate at the
ends is developed the very high voltage. The high voltage produce the
electric field. So you can wrote: "the electric field is a direct
consequence of voltage developed in the ends of the transmitting
antenna". This electric field generate the magnetic field and so on. So
the Hertz' dipole has the three sources of waves. The centre and the two
ends.
It seams that waves from the centre are mainly transverse and that from
the ends mainly longitudinal.
Long wire antennas have many sources. Directional patern is number source
dependent.

You do not like the word voltage. May be the better is polarity.

R. Clark wrote: "Actually you have mixed up two different characteristics.
Polarity
and polarization are NOT the same thing. With RF radiation, the wave
is constantly changing polarity (that is why the source of RF is
called alternating current), but within the "line of sight" of the
antenna, the polarization for a dipole is defined by its angle to the
earth as viewed by the observer.

If you see an horizontal dipole, it produces alternating polarities of
waves with horizontal polarization. If you see a vertical dipole, it
produces alternating polarities of waves with vertical polarization."


The directions in which the
H and E fields act, in the plane transverse to the direction of
propagation, are mutually perpendicular and the direction in which the E
field acts, by convention, defines the polarisation.

Thus a single EM wave has a single, plane, polarisation. Different
combinations of waves are possible such as circular polarisation and,
more generally, elliptical polarisation, but these can always be resolved
into orthogonal plane components.

Simple antennas like straight-wire dipoles and loops transmit and respond
to plane polarised EM waves. More complicated antennas can be made to
transmit and receive circular polarisation of one sense or the other, and
generally an antenna will tend to transmit or be sensitive to some
combination of different plane polarisations. In addition to radiated EM
waves, there are also induction fields in a region close to the antenna.

In a system that contains no anisotropic material (e.g. magnetised
ferrite), when the distance between transmitting and receiving antennas
is at least tens of wavelengths, the principle of reciprocity applies.
By this principle the properties of an antenna when transmitting are the
same as when it is receiving - the properties including the polarisation,
radiation pattern and terminal impedance.

If you find any of this interesting, please don't believe what I've
written here but go to a technical library (e.g. at a University) and
look up the authoritative sources - books on antennas and propagation by
Kraus, Jasik, Jordan and Balmain, Terman, etc.

Do they use the vord voltage?

Please _do not_ respond here telling me or the group that EM waves are
longitudinal and are not polarised.

EM waves by Heaviside are transverse. Now we should check if he was right.
S*


Evidently not from 'the physics that real-life radio communication depends
upon, and was designed by'.

Who is A* ? ... the person who wrote:

Does one wave has many polarizations, or one antenna has many
polarizations?
Which one: transmitter or receiver? Could you teach me?
A*

Chris

Art wrote:
"Thus if we have a radiator of one WL that is tipped in space and near
zero resistance in impedance metric we will then attain a spherical
radiation pattern with Poynting`s vector and thus a demonsration of
point radiation together with further evidence that radiation is of
particle and not of waves."

No matter how Art`s words were combined, I don`t see in them any such
evidence. Even Art agrees that Maxwell`s equations correctly produce
answers to where the energy goes.

The 1955 edition of Terman`s "Electronic and Radio Engineering" shows
the radiation pattern of one WL of wire in Fig. 23-4 (b) on page 867. It
consists of four lobes each making an angle of 54 degrees with the axis
of the wire. The pattern deviates from a spherical pattern by a lot. So
much for "equilibrium"!

Cecil pointed out that in physics, electromagnetic radiation is treated
with duality, using either particle theory or waves, whichever is more
convenient for the problem at hand.

Maxwell solved the problems of radiation using wave equations which are
said to be four of the most influential equations in science.

On page 864 of Terman`s 1955 opus he writes:
"The laws governing such radiation are obtained by using Maxwell`s
equations to express the fields associated with the wire; when this is
done there is found to be a component, termed the radiated field, having
a strength that varies inversely with distance.

If Art would just absorb Terman`s chapter on "Antennas" I doubt he would
write such nonsense.

Best regards, Richard Harrison, KB5WZI

U¿ytkownik "Richard Clark" napisa³ w wiadomo¶ci
...
On Sun, 13 Sep 2009 19:57:22 +0200, Szczepan Bia?ek
wrote:

EM waves by Heaviside are transverse. Now we should check if he was right.

You have confused the telegrapher's equations with propagation.

Before you recite an authority, you really need to understand them.

It is commonly known: "Heaviside said that mathematics was an experimental
science. He organised Maxwell's mathematical work into the four equations
which we now call "Maxwell's Equations".

Maxwell made the model of solid ether. The four equations by Heaviside is
rather "fluid analogy".

"Now Heaviside had the concept of the TEM Wave, which Kelvin and Preece did
not. With these two formulae, he could give a gloss of mathematical style to
his assertion that, properly treated, a slab of energy current could
propagate at the speed of light without distortion. This assertion had
massive practical implications, but Heaviside was obstructed for decades."
From: http://www.ivorcatt.com/2810.htm
S*