Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

At first, there is no standing wave, until the wave reaches the point of
reflection
in the antenna and heads back the way it has come (because not all has been
radiated*****)
On the way back, it againn suffers the losses described above, as well as
radiating a
bit more.

It then reaches the other end and suffers further reflections ad infinitum.

An interesting conclusion is, therefore, that the I2R losses are repeated,
each tiome with a smaller loss, as the wave decrements.

***** Without the remnants of non-radiated power, there could NOT be
a standing wave!

On 01/11/14 15:26, gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

At first, there is no standing wave, until the wave reaches the point of
reflection
in the antenna and heads back the way it has come (because not all has been
radiated*****)
On the way back, it again suffers the losses described above, as well as
radiating a
bit more.

It then reaches the other end and suffers further reflections ad infinitum.

An interesting conclusion is, therefore, that the I2R losses are repeated,
each time with a smaller loss, as the wave decrements.

***** Without the remnants of non-radiated power, there could NOT be
a standing wave!

I don't think anybody would dispute what you say here, so what's to discuss?
--
;-)
..
73 de Frank Turner-Smith G3VKI - mine's a pint.
..
http://turner-smith.co.uk
..
Ubuntu 12.04
Thunderbirds are go.

On 01/11/2014 16:17, Frank Turner-Smith G3VKI wrote:
On 01/11/14 15:26, gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

At first, there is no standing wave, until the wave reaches the point of
reflection
in the antenna and heads back the way it has come (because not all has
been
radiated*****)
On the way back, it again suffers the losses described above, as well as
radiating a
bit more.

It then reaches the other end and suffers further reflections ad
infinitum.

An interesting conclusion is, therefore, that the I2R losses are
repeated,
each time with a smaller loss, as the wave decrements.

***** Without the remnants of non-radiated power, there could NOT be
a standing wave!

I don't think anybody would dispute what you say here, so what's to
discuss?

I would dispute the statement "Without the remnants of non-radiated
power, there could NOT be a standing wave!"

But I'm not as clever as Gareth, so I'll sit at the back of the room
with my dunce's cap on and keep quiet :-)

Frank Turner-Smith G3VKI wrote:
On 01/11/14 15:26, gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

At first, there is no standing wave, until the wave reaches the point of
reflection
in the antenna and heads back the way it has come (because not all has been
radiated*****)
On the way back, it again suffers the losses described above, as well as
radiating a
bit more.

It then reaches the other end and suffers further reflections ad infinitum.

An interesting conclusion is, therefore, that the I2R losses are repeated,
each time with a smaller loss, as the wave decrements.

***** Without the remnants of non-radiated power, there could NOT be
a standing wave!

I don't think anybody would dispute what you say here, so what's to discuss?

It is nonsense, they can be no wave in the element due to it being a
conductor. He is confusing the I and V plots for waves.

"Brian Reay" wrote in message
...
It is nonsense, they can be no wave in the element due to it being a
conductor.

You seem to be unaware that a travelling wave around a wire is what
causes the wave to move along the wire, and not the electrons inside,
which only oscillate a very short distance about their mean.

He is confusing the I and V plots for waves.

There is no confusion on my part. Perhaps you could explain where you
think I am confused, for I had not mentioned the separated I and V
waveforms.

Perhaps you are confused yourself, perhaps, by the current maximum
at the centre of a dipole, for it is not a DC maximum but rises and falls
in magnitude?

gareth wrote:
"Brian Reay" wrote in message
...
It is nonsense, they can be no wave in the element due to it being a
conductor.

You seem to be unaware that a travelling wave around a wire is what
causes the wave to move along the wire, and not the electrons inside,
which only oscillate a very short distance about their mean.

You seem to be unaware that current is the total, net movement of all
the electrons in a wire, not just a single electron.

He is confusing the I and V plots for waves.

There is no confusion on my part. Perhaps you could explain where you
think I am confused, for I had not mentioned the separated I and V
waveforms.

Yeah, right.

Perhaps you are confused yourself, perhaps, by the current maximum
at the centre of a dipole, for it is not a DC maximum but rises and falls
in magnitude?

Only a very confused individual would babble on about the instantaneous
current or voltage.



--
Jim Pennino

"Brian Reay" wrote in message
...
It is nonsense, they can be no wave in the element due to it being a
conductor. He is confusing the I and V plots for waves.

OK, I realise now where your confusion has arisen. It is because I
was discussing what was necessary to set up a standing wave in the
first place, whereas you misunderstood and became confused because
you were discussing the state of affairs AFTER the standing wave had been
set up.

Perhaps if you read posts more carefully and were not so intent on scoring
points and abusing those with whom you deliberately disagree?

gareth wrote:
Ignoring, for the moment, travelling wave antenna, and restricting
discussion to standing wave antennae ...

An antenna is an antenna.

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

Nope, voltage is applied to an antenna causing currents to be created
which in turn cause an electromagnetic field to be created.

As antennas are made of real materials they have a resistance and the
current through that resistance leads to losses.

However, in the real world most antennas have an impedance in the tens
of Ohms while the resistance is in milliohms, so normally the losses
are trivial compared to the radiation.

At first, there is no standing wave, until the wave reaches the point of
reflection
in the antenna and heads back the way it has come (because not all has been
radiated*****)
On the way back, it againn suffers the losses described above, as well as
radiating a
bit more.

Pure nonsense.

It then reaches the other end and suffers further reflections ad infinitum.

Pure nonsense.

An interesting conclusion is, therefore, that the I2R losses are repeated,
each tiome with a smaller loss, as the wave decrements.

A nonsense conclusion based on a nonsense assumption.

***** Without the remnants of non-radiated power, there could NOT be
a standing wave!

Sigh.


--
Jim Pennino

wrote in :

A wave is launched, and radiates SOME of the power, and suffers
both I2R losses and dielectric and permeability losses associated
with creating and collapsing the near field.

Nope, voltage is applied to an antenna causing currents to be created
which in turn cause an electromagnetic field to be created.

As antennas are made of real materials they have a resistance and the
current through that resistance leads to losses.

However, in the real world most antennas have an impedance in the tens
of Ohms while the resistance is in milliohms, so normally the losses
are trivial compared to the radiation.


I'm glad you're doing this. Rather than get into technicalities I'm not sure
of, I'll just say I'm glad to see a counterpoint that doesn't make me wonder
if Ohm's and Watt's laws mean anythign anymore, and wonder if I'm missing
something I shouldn't when seeign phrases like 'launching a wave' or 'feeding
power', when all I have ever learned has taught me that power is DRAWN ON,
not FORCED INTO.

I'll explain in off-topic manner why I'm glad this is happening... I was
raised listening to Schubert, Chopin, Bach, Lizst, etc, hearing them on a
piano played by a mother who might have been a concert pianist for a living
if she hadn;t feared fame and decised to marry and have kids. Later, having
left home, I began to miss what I had taken for granted. And one day I heard
soem geezer ona radio say that Chopin left hand parts were 'metronomic'. I
was shocked! Had I missed something this scholarly pronouncement was informed
by, something years of actually hearign real performace throughout my entire
childhood had missed?!

The answer, of course, is NO. The guy was like the emperor sounding off about
his new clothes. A Chopin left hand part is not metronomic. It anchors what
the right hand is doing, but it shifts in its own right, delivering the line
like a well spoken phrase. It moves with thwe mass, not against it. Just like
theory moves with discovery, not against it.

It can be easy to get lost in difficult things. Worse yet, ONE repeated,
inane, or insane, pronouncement can produce real doubt. A human brais is
highly fallible! I went to a shop fpor years, saw the same floor day in, day
out. One day they changed it. To this day I do NOT recall that old floor.

I hope this off-topic rant hasn't doen more harm than good, but I felt like I
should do it, to explain in several ways at once why repeated careful
correction of a repeated error is important. It might not change the person
making the error, but it will almost certainly help prevent other people
losing thweior footing on a track they'd thought secure.

Incidentally, I know from my own coding efforts that unlearning bad habits is
usually a greater task than learning new, better ones! Sometimes I tire of
repetition, but a bit more patience is in order. Context is eveything. It
depends what is being repeated.

We're all vulnerable to wanting renewal, and can grab for it when it's not
really there. Real new stuff usually only becomes apparent when all the old
has been explored and found wanting, so when old familiar theory gets
repeated and NOT found wanting, there's some real relief there. New stuff
will be built on it, it won't come by discarding it like it means nothing.

This has been a longwinded, but I hope convincing way of saying that I think
what you're doing is worth doing. Saying less might not have meant nearly as
much.

The basic problem is wider too, the internet at large is full of data, not so
much info, and even less wisdom, which used to be easier to come by than it
is now.

"Lostgallifreyan" wrote in message
. ..

Eh?