Standing waves
 

On Fri, 18 Sep 2009 08:51:04 +0200, Szczepan Bia?ek
wrote:

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

"If antenna has only one source"

Thank you for confirming that in spite of quoting me, you just don't
get it.

73's
Richard Clark, KB7QHC

Standing waves
 

"Cecil Moore"
...
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?

Each dipole has visible the two radials (sometimes end parts of the
transmitting line). Each radials has the one strong source at the end like
the Kundt's tube. See: http://en.wikipedia.org/wiki/Kundt's_tube
A dipole has the two radials so it has at least the two strong sources.
Only the two if it is shorter then WL. If it is longer than WL then appear
the next sources on the both radials at each 1/2WL from the end.

I will be absent till Monday evening.
S*

Standing waves
 

"Richard Clark" wrote
...
On Fri, 18 Sep 2009 08:51:04 +0200, Szczepan Bia?ek
wrote:

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

"If antenna has only one source"

Thank you for confirming that in spite of quoting me, you just don't
get it.

You go into details.
In the Gas Analogy the monopole antena is exactly like the Kundt's tube.
See: http://en.wikipedia.org/wiki/Kundt's_tube
A dipole has the two Kundt's tubes.
S*

Standing waves
 

On Fri, 18 Sep 2009 03:47:19 -0700 (PDT), Richard Fry
wrote:

so those locations
generate very little of the total EM radiation from these antennas.

Hi Richard,

The entire radiator radiates, not just portions of it. The phase,
time, distance relationships along the length contribute to a myriad
of characteristics, but they are not separable from the complete
contribution.

73's
Richard Clark, KB7QHC

Standing waves
 

On Fri, 18 Sep 2009 18:33:00 +0200, Szczepan Bia?ek
wrote:

You go into details.

Yes, I do go into the details.

In the Gas Analogy the monopole antena is exactly like the Kundt's tube.

Analogy is a false arguement. In the car-seen-at-a-distance analogy,
this proves that only midgets or pygmies drive cars because we are too
big to fit into such small things seen in the distance.

73's
Richard Clark, KB7QHC

Standing waves
 

Richard Clark wrote:
The entire radiator radiates, not just portions of it. The phase,
time, distance relationships along the length contribute to a myriad
of characteristics, but they are not separable from the complete
contribution.

Using the method of moments, each segment contributes
radiation proportional to the net current in the segment.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

Standing waves
 

"Richard Clark" wrote
...
On Fri, 18 Sep 2009 18:33:00 +0200, Szczepan Bia?ek
wrote:

You go into details.

Yes, I do go into the details.

In the Gas Analogy the monopole antena is exactly like the Kundt's tube.

Analogy is a false arguement.

Heaviside did the Hydraulic Analogy. All is exactly the same like in the
fluids mechanics.
Next the electrons were discovered. Automatically Heaviside is a history and
the Gas Analogy is in power.


In the car-seen-at-a-distance analogy,
this proves that only midgets or pygmies drive cars because we are too
big to fit into such small things seen in the distance.

But you, radio people, are very close to waves and should be easy for you to
work out the answer for the Question:
Which Analogy is right?

I will be absent till Monday evening.
S*

Standing waves
 

On Fri, 18 Sep 2009 19:13:17 +0200, Szczepan Bia?ek
wrote:

All is exactly the same like in the fluids mechanics.

"Exactly" makes it very, very easy to show how an analogy fails:
Describe the laminar flow in terms of
the Reynolds number for
the interface between RF and a Biconical Antenna
and
the interface between RF and a thin wire Antenna.

If you do not understand
1. the terms of fluid mechanics and/or
2. cannot complete this request, then
your analogy has failed.

I won't wait for that obvious failure. This is several steps above
your pay-grade. So, you should really attempt to work on first
principles rather than rummaging in the attic for impressive artifacts
of science. The musty chestnuts you find would poison a dog.

73's
Richard Clark, KB7QHC

Standing waves
 

"Szczepan Bialek" wrote in message
...

"Richard Clark" wrote
...
On Fri, 18 Sep 2009 18:33:00 +0200, Szczepan Bia?ek
wrote:

You go into details.

Yes, I do go into the details.

In the Gas Analogy the monopole antena is exactly like the Kundt's tube.

Analogy is a false arguement.

Heaviside did the Hydraulic Analogy. All is exactly the same like in the
fluids mechanics.
Next the electrons were discovered. Automatically Heaviside is a history
and the Gas Analogy is in power.


In the car-seen-at-a-distance analogy,
this proves that only midgets or pygmies drive cars because we are too
big to fit into such small things seen in the distance.

But you, radio people, are very close to waves and should be easy for you
to work out the answer for the Question:
Which Analogy is right?

I will be absent till Monday evening.
S*


neither analogy is 'right'. they are useful in limited circumstances to
demonstrate some basic pressure wave physics to young students. but neither
one properly reproduces electromagnetic waves.

Standing waves
 

Richard Clark wrote:
On Fri, 18 Sep 2009 19:13:17 +0200, Szczepan Bia?ek
wrote:

All is exactly the same like in the fluids mechanics.

"Exactly" makes it very, very easy to show how an analogy fails:
Describe the laminar flow in terms of
the Reynolds number for

Hmm, I think I'd start with a very long K1FO yagi, say 50 elements.
Maybe even extend one to 100 elements to getting very fine details.
Then we look at the longitoodordinal current along the horizontal
element by element. I'll have to work on it a while though.

What are you thinking?

73's
Richard Clark, KB7QHC

tom
K0TAR