On Wed, 2 Feb 2011 09:35:38 +0100, "Antonio Vernucci"
wrote:

This is clearly due to the fact that the external body of the trap (an aluminuim
can about 2 feet long), which contains two coils resonated at different
frequencies by means of built-in capacitors, is effectively part of the antenna
radiating element. So, the trap is a bipole not only comprising lumped elements,
and that is the reason why it cannot be inverted.

Hi Antonio,

No, in fact.

You clearly state in the first sentence the reason why.

The external body renders an asymmetry. The two elements it separates
are also non-symmetrical (both physically and electrically).

This is NOT a lumped circuit exercise that has gone bad.

73's
Richard Clark, KB7QHC

On Feb 2, 3:42*am, "Antonio Vernucci" wrote:
Tom,

the story began when, a few days ago, I was going to replace a trap of my HF
yagi. Not to make mistakes, I consulted the antenna assembly manual where I
found a big banner: do not invert traps otherwise the antenna will not work.

So, I thought, this is a case in which a bipole cannot be inverted.

This is clearly due to the fact that the external body of the trap (an aluminuim
can about 2 feet long), which contains two coils resonated at different
frequencies by means of built-in capacitors, is effectively part of the antenna
radiating element. So, the trap is a bipole not only comprising lumped elements,
and that is the reason why it cannot be inverted.

So, as K1TTT has pointed out, a bipole can be inverted without consequences only
if it has only 2 ports, has only passive linear components, and is small enough
to be considered a lumped element.

73

Tony I0JX
Rome, Italy

A bipole is symmetrical, obviously the internal circuity of the trap
is not symmetrical .

Jimmie

A bipole is symmetrical, obviously the internal circuity of the trap
is not symmetrical .

Jimmie, that is not the point.

- if the bipole is made of lumped components, then it can be freely reversed
without consequences, independently of whether it is symmetrical or asymmetrical

- a trap, which instead contains a distributed element (that is the radiating
trap body), can be freely reversed without consequences only if it is
symmetrical (which is not my case).

73

Tony I0JX

Hello Tony,

On 2 feb, 19:14, "Antonio Vernucci" wrote:
A bipole is symmetrical, obviously the internal circuity of the trap
is not symmetrical *.

Jimmie, that is not the point.


At some frequency, everything becomes a distributed component, it
depends on size/lambda ratio and application. Many distributed
components can be modelled based on theoretical lumped components
(with sufficient accuracy), but a ground for modelling stray
capacitance is frequently required.

True lumped component behaviour, in my opinion, only applies to
networks with size=0.

- if the bipole is made of lumped components, then it can be freely reversed
without consequences, independently of whether it is symmetrical or
asymmetrical

What do you define as "lumped component"?

- a trap, which instead contains a distributed element (that is the radiating
trap body), can be freely reversed without consequences only if it is
symmetrical (which is not my case).


I agree on the above.


73

Tony I0JX

Best regards,


Wim
PA3DJS
www.tetech.nl
without abc, PM will reach me

On Feb 2, 3:53*pm, "Szczepan Bialek" wrote:
"Wimpie" napisal w ...

On 2 feb, 09:37, "Antonio Vernucci" wrote:

For the limitation on lumped circuit approach, it is not important
whether or not it contributes to the overall radiation of a
structure. *When you make a floating ground out of 4 quarter-wave
radials (monopole?), this structure has minor influence on the far
field pattern of the quarter wave (or better half wave) radiator above
it.

Inhttp://www.padrak.com/ine/FARADAY1.html*Faraday wrote:

"The view which I am so bold to put forth considers, therefore, radiation as
a kind of species of vibration in the lines of force which are known to
connect particles and also masses of matter together. It endeavors to
dismiss the aether, but not the vibration. The kind of vibration which, I
believe, can alone account for the wonderful, varied, and beautiful
phaenomena of polarization, is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids, for
the vibrations in these cases are direct, or to and from the centre of
action, whereas the former are lateral. It seems to me, that the resultant
of two or more lines of force is in an apt condition for that action which
may be considered as equivalent to a lateral vibration; whereas a uniform
medium, like the aether, does not appear apt, or more apt than air or
water."

I hope you can read what you quoted above and understand it... note
specifically:

It endeavors to
dismiss the aether, but not the vibration.

so with this he has decided there is NO aether!

is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids,

so all the comparisons to water waves or sound waves are NOT correct!

equivalent to a lateral vibration

NOT longitudinal!

so by these statements he has said that electromagnetic waves ARE NOT
caused by an aether, and ARE lateral, NOT longitudinal... and CAN NOT
be compared to sound or water vibrations!

On Feb 2, 7:06*pm, Wimpie wrote:
Hello Tony,

On 2 feb, 19:14, "Antonio Vernucci" wrote:

A bipole is symmetrical, obviously the internal circuity of the trap
is not symmetrical *.

Jimmie, that is not the point.

At some frequency, everything becomes a distributed component, it
depends on size/lambda ratio and application. *Many distributed
components can be modelled based on theoretical lumped components
(with sufficient accuracy), but a ground for modelling stray
capacitance is frequently required.

True lumped component behaviour, in my opinion, only applies to
networks with size=0.

'True' or theoretical versus 'practical' is a very important
distinction that is, or at least was, taught in engineering classes.
it is very important to know when you can apply the practical
simplifications that allow you to do design work without worrying
about insignificant phenomena in the problem domain you are working
in... so if i am designing an HF antenna I know that objects below a
given size can be safely ignored, but if i'm doing a microwave design
i have to take into account much smaller objects.

"K1TTT" napisal w wiadomosci
...
On Feb 2, 3:53 pm, "Szczepan Bialek" wrote:

Inhttp://www.padrak.com/ine/FARADAY1.html Faraday wrote:

"The view which I am so bold to put forth considers, therefore, radiation
as
a kind of species of vibration in the lines of force which are known to
connect particles and also masses of matter together. It endeavors to
dismiss the aether, but not the vibration. The kind of vibration which, I
believe, can alone account for the wonderful, varied, and beautiful
phaenomena of polarization, is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids, for
the vibrations in these cases are direct, or to and from the centre of
action, whereas the former are lateral. It seems to me, that the resultant
of two or more lines of force is in an apt condition for that action which
may be considered as equivalent to a lateral vibration; whereas a uniform
medium, like the aether, does not appear apt, or more apt than air or
water."

I hope you can read what you quoted above and understand it... note
specifically:

It endeavors to
dismiss the aether, but not the vibration.

so with this he has decided there is NO aether!

Ik such words: "I suppose we may compare together the matter of the aether
and ordinary matter (as, for instance, the copper of the wire through which
the electricity is conducted), and consider them as alike in their essential
constitution; i.e. either as both composed of little nuclei, considered in
the abstract as matter"

In your antennas and in the space are free electrons. We do not need a
mystery aether.

is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids,

so all the comparisons to water waves or sound waves are NOT correct!

You know that the dipole works like the two loudspeakers.

equivalent to a lateral vibration

NOT longitudinal!

And not traversal. The waves radiated from the two ends of a dipole I call
"coupled".

so by these statements he has said that electromagnetic waves ARE NOT
caused by an aether, and ARE lateral, NOT longitudinal... and CAN NOT
be compared to sound or water vibrations!

Faraday was great. In the Nature no natural acoustic dipoles. For him was
obvious that must be something equivalent to a lateral vibration.
As you know it is the two or more sources of pressure waves properly phased.

Are electrons jumping off from your transmitting antennas?
In copper and in space are the same "little nuclei, considered in the
abstract as matter". Electrons have mass.

Biot-Savart's magnetic whirl is massles.
S*

On Feb 2, 7:53*pm, "Szczepan Bialek" wrote:
*"K1TTT" napisal w ...
On Feb 2, 3:53 pm, "Szczepan Bialek" wrote:





Inhttp://www.padrak.com/ine/FARADAY1.htmlFaraday wrote:

"The view which I am so bold to put forth considers, therefore, radiation
as
a kind of species of vibration in the lines of force which are known to
connect particles and also masses of matter together. It endeavors to
dismiss the aether, but not the vibration. The kind of vibration which, I
believe, can alone account for the wonderful, varied, and beautiful
phaenomena of polarization, is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids, for
the vibrations in these cases are direct, or to and from the centre of
action, whereas the former are lateral. It seems to me, that the resultant
of two or more lines of force is in an apt condition for that action which
may be considered as equivalent to a lateral vibration; whereas a uniform
medium, like the aether, does not appear apt, or more apt than air or
water."
I hope you can read what you quoted above and understand it... note

specifically:

It endeavors to
dismiss the aether, but not the vibration.
so with this he has decided there is NO aether!

Ik such words: "I suppose we may compare together the matter of the aether
and ordinary matter (as, for instance, the copper of the wire through which
the electricity is conducted), and consider them as alike in their essential
constitution; i.e. either as both composed of little nuclei, considered in
the abstract as matter"

In your antennas and in the space are free electrons. We do not need a
mystery aether.

is not the same as that which occurs on the
surface of disturbed water, or the waves of sound in gases or liquids,
so all the comparisons to water waves or sound waves are NOT correct!

You know that the dipole works like the two loudspeakers.

equivalent to a lateral vibration
NOT longitudinal!

And not traversal. The waves radiated from the two ends of a dipole I call
"coupled".

so by these statements he has said that electromagnetic waves ARE NOT

caused by an aether, and ARE lateral, NOT longitudinal... and CAN NOT
be compared to sound or water vibrations!

Faraday was great. In *the Nature no natural acoustic dipoles. For him was
obvious that must be something equivalent to a lateral vibration.
As you know it is the two or more sources of pressure waves properly phased.

Are electrons jumping off from your transmitting antennas?
In copper and in space are the same "little nuclei, considered in the
abstract as matter". Electrons have mass.

Biot-Savart's magnetic whirl is massles.
S*

no, electrons don't jump off my antennas, and there can not be free
electrons in space or they would all repel each other and fly away.
and since they have mass and other detectable properties we would
easily be able to measure them if they were conducting electromagnetic
waves, such a simple thing as speed of the wave would be VERY
different than what we measure now.

On Feb 2, 12:42*am, "Antonio Vernucci" wrote:
Tom,

the story began when, a few days ago, I was going to replace a trap of my HF
yagi. Not to make mistakes, I consulted the antenna assembly manual where I
found a big banner: do not invert traps otherwise the antenna will not work.

So, I thought, this is a case in which a bipole cannot be inverted.

This is clearly due to the fact that the external body of the trap (an aluminuim
can about 2 feet long), which contains two coils resonated at different
frequencies by means of built-in capacitors, is effectively part of the antenna
radiating element. So, the trap is a bipole not only comprising lumped elements,
and that is the reason why it cannot be inverted.

So, as K1TTT has pointed out, a bipole can be inverted without consequences only
if it has only 2 ports, has only passive linear components, and is small enough
to be considered a lumped element.

73

Tony I0JX
Rome, Italy

As I see it, it has nothing to do with being small enough to be
considered a lumped element. Instead, it has to do with coupling
between the network elements and the outside world. Clearly your
trap is coupled to the outside world. Clearly the series LC in my
example is coupled to its surroundings. In such cases, you're NOT
dealing with a two-terminal network: there is a path for current
other than the two terminals. You can put as many transmission lines
in your network as you wish, and as long as they don't have coupling
to the rest of the universe except through the two closely-spaced
terminals, there will be no difference in behaviour if you reverse the
terminals. If you can show a valid counter-example, you've proven a
whole lot of textbooks wrong...

I suppose equivalently, if you decouple your measurement from the rest
of the universe, you'll get the same result. Typical broadband
directional couplers (of the sort used in S-parameter test sets) have
good decoupling, to be able to separate excitation from return power.

Cheers,
Tom

In my first EE class, 'way back in the fall of 1962, the instructor
walked in and said "We shall study LLFPB", by which he meant

Lumped, Linear, Finite, Passive, and BILATERAL

so I'd have to conclude that your bipole is one or more of
not lumped and/or
not linear and/or
not finite and/or
not passive.

Yesterday, while repairing my antenna, something came to my mind I had never
focused on before.

Let us consider a bipole, that is a "black box" having TWO terminals and
including plain passive elements only (like capacitors, inductors, ... , no
diodes or other special devices), arranged the way you prefer, it does not
matter.

Instead of directly telling which it is, just for fun I wonder whether anyone
can figure out a case in which a bipole may not be reversed without
consequences. Not difficult, but it anyway requires some thinking.
--
-- Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member & Certified Instructor for Rifle, Pistol, & Home Firearm Safety
Also Certified Instructor for the Kansas Concealed-Carry Handgun (CCH) license