Antenna physical size
 

On Mar 9, 9:23 am, Art Unwin wrote:
On Mar 9, 7:16 am, wrote:

Art,
"Why are so many hams alarmed at the idea?"
Because of the way you describe things, words used for a distinction
between things that just don't make sense. At least that's why I
'wonder' at times. After seeing your 'methods' of doing/saying
things, you just don't 'alarm' me much. You DO make me 'wonder'
though...
- 'Doc

You may be right We will just have to wait and see how things turn
out.
If it works then I am smart and if it is useless then I fit what
everybody
thinks of me. No damage done either way.

My replacement antenna for the one I sent away is comming along just
fine
and I will probably be active on the air in a few weeks.
The new one is about two shoe box size and will be connected to a tilt/
scan
mechanism so that I can fully determine all the characteristics in
real life circumstances.
The frequency spread is down to the top of the broadcast band and it
will be controlled by my
Icom where I will disconect the inbuilt tuner motors and reconnect to
my antenna.
This should then ensure that the antenna is always in equilibrium
screw driver style
when I am on the air regardless of the band in use.Hoping to change
polarity in QSO's
to investigate the differences. Hopefully this summer the pan tilt
will also be made
automatic for best polarity reception which will then allow for the
addition of a dish reflector.
Bought myself a new thin Mac laptop which is exciting to use. There is
a free NEC 2
program available(cocoanec) so it is getting difficult to determine
what to work on.
Spring is coming and life is good despite the naysayers.
Have a happy day
Regards
Art

Antenna physical size
 

Art Unwin wrote:
On Mar 7, 11:46 am, Jim Lux wrote:

wrote:

I have searched quite a bit for evidence that states that performance
of antennas can be rated by it's size. Formulas do not refere to
radiator size or volume
and aparture is referenced to gain. I understand that sort of thinking
based on Yagi design
but the idea that all small radiators are inefficient is rather
ludicrouse. My work, based on
the sciences of the masters, show that a efficient radiator can be any
size,shape and
configuration as long as it
is in equilibrium . Period
No where can I find reference to "size" in what the masters state
Regards
Art

The work by Chu (Journal of Applied Physics, p1163, v19, Dec 1948) and
subsequently by Harrington (IEEE Trans Ant & Prop, V18#6, Nov 1965,
p896) , Thiele (IEEE Trans on Ant and Prop, v51, #6, June 2003, p1263)
and later others, discusses fundamental limits on performance. Watch
out, though, for the assumptions in the constraints (e.g. whether the
device attached to the feedpoint is reciprocal), and, of course, where
the boundary of the system is.

Watch out also for the definition of "Q", which in this context is the
ratio of stored to disspated/radiated energy, not the ratio of center
frequency/bandwidth.

In short, there is a tradeoff between Q, directivity, and size. And,
because high Q implies high stored energy, for physically realizable
antennas with loss, efficiency is in the mix too.

Googling "chu harrington limit" often turns up useful stuff.


Googled Chu harrington and find that his work is basically empirical
around known arrangements.
When he brought the question of Q into the picture he made the
statement that small antennas
are usually of a low impedance which is correct empirically with
respect to existing designs but it is not exclusive

To summate, my antenna design is considered small yet complies with
Maxwells laws and yet does not have a narrow bandwidth or low
impedance thus Chu's comments cannot be inclusive of all radiators.
Best regards
Art

which is why I mentioned:
"Watch out, though, for the assumptions in the constraints"

However, I believe it is incorrect to characterize his analysis as
empiricism (i.e. getting experimental data and fitting curves). His
analysis (and that of Harrington and Thiele) is entirely theoretical,
and actually doesn't deal with loss in the antenna, per se. Indeed,
Chu's analysis is based on a simple case (a dipole), but that's more
because it's a good first example (and he could use the previous work of
Schelkunoff as a starting point). I believe the analysis is generally
valid, regardless of what the actual antenna is.

Antenna physical size
 

On Mar 10, 11:19 am, Jim Lux wrote:
Art Unwin wrote:
On Mar 7, 11:46 am, Jim Lux wrote:

wrote:

I have searched quite a bit for evidence that states that performance
of antennas can be rated by it's size. Formulas do not refere to
radiator size or volume
and aparture is referenced to gain. I understand that sort of thinking
based on Yagi design
but the idea that all small radiators are inefficient is rather
ludicrouse. My work, based on
the sciences of the masters, show that a efficient radiator can be any
size,shape and
configuration as long as it
is in equilibrium . Period
No where can I find reference to "size" in what the masters state
Regards
Art

The work by Chu (Journal of Applied Physics, p1163, v19, Dec 1948) and
subsequently by Harrington (IEEE Trans Ant & Prop, V18#6, Nov 1965,
p896) , Thiele (IEEE Trans on Ant and Prop, v51, #6, June 2003, p1263)
and later others, discusses fundamental limits on performance. Watch
out, though, for the assumptions in the constraints (e.g. whether the
device attached to the feedpoint is reciprocal), and, of course, where
the boundary of the system is.

Watch out also for the definition of "Q", which in this context is the
ratio of stored to disspated/radiated energy, not the ratio of center
frequency/bandwidth.

In short, there is a tradeoff between Q, directivity, and size. And,
because high Q implies high stored energy, for physically realizable
antennas with loss, efficiency is in the mix too.

Googling "chu harrington limit" often turns up useful stuff.

Googled Chu harrington and find that his work is basically empirical
around known arrangements.
When he brought the question of Q into the picture he made the
statement that small antennas
are usually of a low impedance which is correct empirically with
respect to existing designs but it is not exclusive
To summate, my antenna design is considered small yet complies with
Maxwells laws and yet does not have a narrow bandwidth or low
impedance thus Chu's comments cannot be inclusive of all radiators.
Best regards
Art

which is why I mentioned:
"Watch out, though, for the assumptions in the constraints"

However, I believe it is incorrect to characterize his analysis as
empiricism (i.e. getting experimental data and fitting curves). His
analysis (and that of Harrington and Thiele) is entirely theoretical,
and actually doesn't deal with loss in the antenna, per se. Indeed,
Chu's analysis is based on a simple case (a dipole), but that's more
because it's a good first example (and he could use the previous work of
Schelkunoff as a starting point). I believe the analysis is generally
valid, regardless of what the actual antenna is.

You may well be correct. I cannot enter the IEEE papers that you
allude to
to study it furthur. The fact that my impedences are high and the
bandwith is large
is really putting me in a unknown area and I have a lot to learn about
it
Regards
Art

Antenna physical size
 

You can pretty much sum up the characteristics of small antennas as:

Small - Broadband - Efficient: Pick any two.

Roy Lewallen, W7EL

Antenna physical size
 

On Mar 10, 1:56 pm, Roy Lewallen wrote:
You can pretty much sum up the characteristics of small antennas as:

Small - Broadband - Efficient: Pick any two.

Roy Lewallen, W7EL

Who knows what "efficiency" represents in the electrical world?
It is the word "small" that confuses everybody when the word
should be" fractional wavelength".
Small and large are meaningles in the antenna world.
No I diddn't overlook the sniping.

Antenna physical size
 

Jimmie D wrote:
"Roy Lewallen" wrote in message
...

You can pretty much sum up the characteristics of small antennas as:

Small - Broadband - Efficient: Pick any two.

Roy Lewallen, W7EL


Don't you mean, You can pretty much sum up the characteristics of antennas
as:

Small - Broadband - Efficient: Pick any two.

Jimmie

And what Chu, Harrington, etc., tell you is a mathematical basis for
that statement.

You can also add "directivity" into the mix.

Antenna physical size
 

Art Unwin wrote:
On Mar 10, 1:56 pm, Roy Lewallen wrote:

You can pretty much sum up the characteristics of small antennas as:

Small - Broadband - Efficient: Pick any two.

Roy Lewallen, W7EL


Who knows what "efficiency" represents in the electrical world?

I think the conventional meaning would be power radiated vs power into
the system.

If you define "power radiated" to mean "power radiated in a particular
direction" then you're adding directivity into the mix.

If you define "power into the system" to be 120V Wall power that's
different than RF power at the feedpoint of the antenna which is
different than RF power out at the output of the transmitter.

So, you have to define the appropriate reference plane. The antenna
literature tends to draw the boundary at the feedpoint of the antenna,
because the rest is "circuit theory".

The ham world tends to draw the boundary at the output of the
transmitter (so we include loss in feedlines and matching networks),
because the FCC power limit is usually measured at that point. (although
nothing in the rules says you can't measure after the matching network)

In the commercial broadcast world, there's a sort of hybrid, because
there's an RF power limit AND a requirement to have a particular field
strength in the far field at a particular distance.



It is the word "small" that confuses everybody when the word
should be" fractional wavelength".


Nope.. small in an absolute sense. An antenna that is 10 times bigger
will have more directivity or other figure of merit. Applies pretty
much whether you're comparing an antenna that is 0.01 wavelength to 0.1
or comparing one that is 10 wavelengths to one that is 100 wavelengths.

What you can't say is that the amount of change from 0.01 to 0.1 is the
same as from 10 to 100.

Small and large are meaningles in the antenna world.

They have meaning as far as relative. large is better than small.
And, "directive" antennas that are small relative to a wavelength tend
to have high Q (in the stored vs radiated energy sense, which may or may
not imply narrow bandwidth)


It's probably worth finding a library that can get you copies of the
papers, rather than relying on interpretations and summaries. The most
common misinterpretation is to conceptually equate antenna Q to antenna
bandwidth.

No I diddn't overlook the sniping.

Antenna physical size
 

"Art Unwin" wrote in message
...
On Mar 8, 12:25 am, "John KD5YI" wrote:
"Brian Kelly" wrote in message

...
On Mar 7, 6:09 pm, Art Unwin wrote:



On Mar 7, 4:45 pm, "Dave" wrote:

"Art Unwin" wrote in message

...

On Mar 7, 2:08 pm, (Richard Harrison)
wrote:
I disagree. Laws written are all based on the assumption of
equilibrium and that includes
Maxwell's laws. These laws hav e zero refernce to size as such
though
many would seek

because contrary to what those male enhancement product adds tell you,
size
doesn't matter.

for the word volume. Pertinent factors are wave length of frequency
in
The problem here is that amateur radio is wellded to the yagi design
which is not one of equilibrium

WAIT JUST ONE GOSH DARN MINUTE! you have said in the past that the
simple
half wave dipole WAS a prefect example of equilibrium! NOW it
isn't???
have you had a new revelation while i had your old email address
plonked??

David,
You admit to not understanding the term "equilibrium" so what do you
care what I say and in what content.
If you consider a half wave dipole as being in equilibrium you have to
consider the electrical circuit
consisting of a capacitance from the antenna to ground or the route
thru the center of of the radiator, both of thes circuits
can be considered as being in equilibrium. However, on this newsgroup
a fractional wavelength radiator is considered as an open circuit for
some reason and thus under those circumstances the half wave dipole is
not in equilibrium.
Now your views on radiation is all over the place so it is very hard
for me to determine the context of what you say.
Art

Long before we rode our dinosaurs to club meetings the bright lights
had completely agreed that the strength of radio signals at far off
places was a function of the integral of i·dl where dl is the bigness
of the aerial. Maybe it's in Sears and Zemansky. I dunno . . nor do I
really care.

w3rv

Antennas for All Applications, 3rd Edition, Kraus & Marhefka, McGraw-Hill,
page 12.

Begin quote

Regardless of antenna type, all involve the same basic principle that
radiation is produced by accelerated (or decelerated) charge. The basic
equation of radiation may be expressed simply as

IL = Qv (A m / s)

where

I = time-changing current, A/s
L = length of current element, m
Q = charge, C
v = time change of velocity which equals the acceleration of the charge,
m/s

Thus, time-changing current radiates and accelerated charge radiates. For
steady-state harmonic variation, we usually focus on current. For
transients
or pulses, we focus on charge. The radiation is perpendicular to the
acceleration, and the radiated power is proportional to the square of IL
or
Qv.

end quote

Cheers,
John

John
If Kraus said "The radiation is perpendicular to the accelleration"
then the book is worthless.
Review the scalar quantities of a radiator. It is impossible for the
resultant to be at 90
degrees to the antenna axis. I suspect the roots of this untruth was
the invention of the
planar antenna. For maximum horizontal radiation a radiator will be
around 10 degrees
out of parallel to the earth surface, not parallel.
The king is dead, long live the king. Old books just cannot keep up to
date
Regards
Art
ie the yagi


Art -

I was actually replying to W3RV. However, since you piped up...

Have you had any books on the subject published? How about research papers?
Anything published at all? Do you have any presentations with equations
prepared to support your claim? To which companies have you sold your
expertise in this field? Have your taught any classes?

It is laughable to think anybody would consider you an authority on the
subject, much less a greater authority than Kraus or any other contributor
to this group. You really should get some psychiatric help to quell those
delusions of grandeur you have.

Cheers,
John

Antenna physical size
 

On Mar 11, 8:42 am, "John KD5YI" wrote:
"Art Unwin" wrote in message

...
On Mar 8, 12:25 am, "John KD5YI" wrote:



"Brian Kelly" wrote in message

...
On Mar 7, 6:09 pm, Art Unwin wrote:

On Mar 7, 4:45 pm, "Dave" wrote:

"Art Unwin" wrote in message

....

On Mar 7, 2:08 pm, (Richard Harrison)
wrote:
I disagree. Laws written are all based on the assumption of
equilibrium and that includes
Maxwell's laws. These laws hav e zero refernce to size as such
though
many would seek

because contrary to what those male enhancement product adds tell you,
size
doesn't matter.

for the word volume. Pertinent factors are wave length of frequency
in
The problem here is that amateur radio is wellded to the yagi design
which is not one of equilibrium

WAIT JUST ONE GOSH DARN MINUTE! you have said in the past that the
simple
half wave dipole WAS a prefect example of equilibrium! NOW it
isn't???
have you had a new revelation while i had your old email address
plonked??

David,
You admit to not understanding the term "equilibrium" so what do you
care what I say and in what content.
If you consider a half wave dipole as being in equilibrium you have to
consider the electrical circuit
consisting of a capacitance from the antenna to ground or the route
thru the center of of the radiator, both of thes circuits
can be considered as being in equilibrium. However, on this newsgroup
a fractional wavelength radiator is considered as an open circuit for
some reason and thus under those circumstances the half wave dipole is
not in equilibrium.
Now your views on radiation is all over the place so it is very hard
for me to determine the context of what you say.
Art

Long before we rode our dinosaurs to club meetings the bright lights
had completely agreed that the strength of radio signals at far off
places was a function of the integral of i·dl where dl is the bigness
of the aerial. Maybe it's in Sears and Zemansky. I dunno . . nor do I
really care.

w3rv

Antennas for All Applications, 3rd Edition, Kraus & Marhefka, McGraw-Hill,
page 12.

Begin quote

Regardless of antenna type, all involve the same basic principle that
radiation is produced by accelerated (or decelerated) charge. The basic
equation of radiation may be expressed simply as

IL = Qv (A m / s)

where

I = time-changing current, A/s
L = length of current element, m
Q = charge, C
v = time change of velocity which equals the acceleration of the charge,
m/s

Thus, time-changing current radiates and accelerated charge radiates. For
steady-state harmonic variation, we usually focus on current. For
transients
or pulses, we focus on charge. The radiation is perpendicular to the
acceleration, and the radiated power is proportional to the square of IL
or
Qv.

end quote

Cheers,
John

John
If Kraus said "The radiation is perpendicular to the accelleration"
then the book is worthless.
Review the scalar quantities of a radiator. It is impossible for the
resultant to be at 90
degrees to the antenna axis. I suspect the roots of this untruth was
the invention of the
planar antenna. For maximum horizontal radiation a radiator will be
around 10 degrees
out of parallel to the earth surface, not parallel.
The king is dead, long live the king. Old books just cannot keep up to
date
Regards
Art
ie the yagi

Art -

I was actually replying to W3RV. However, since you piped up...

Have you had any books on the subject published? How about research papers?
Anything published at all? Do you have any presentations with equations
prepared to support your claim? To which companies have you sold your
expertise in this field? Have your taught any classes?

It is laughable to think anybody would consider you an authority on the
subject, much less a greater authority than Kraus or any other contributor
to this group. You really should get some psychiatric help to quell those
delusions of grandeur you have.

Cheers,
John

Let's keep to the subject and put the other comments aside.
Do you have any antenna computor programs that you have confidence in?
What are they so I can give you thr figures to prove it to yourself
Art

Antenna physical size
 

On Mar 11, 9:46 am, Art Unwin wrote:
On Mar 11, 8:42 am, "John KD5YI" wrote:



"Art Unwin" wrote in message

...
On Mar 8, 12:25 am, "John KD5YI" wrote:

"Brian Kelly" wrote in message

....
On Mar 7, 6:09 pm, Art Unwin wrote:

On Mar 7, 4:45 pm, "Dave" wrote:

"Art Unwin" wrote in message

...

On Mar 7, 2:08 pm, (Richard Harrison)
wrote:
I disagree. Laws written are all based on the assumption of
equilibrium and that includes
Maxwell's laws. These laws hav e zero refernce to size as such
though
many would seek

because contrary to what those male enhancement product adds tell you,
size
doesn't matter.

for the word volume. Pertinent factors are wave length of frequency
in
The problem here is that amateur radio is wellded to the yagi design
which is not one of equilibrium

WAIT JUST ONE GOSH DARN MINUTE! you have said in the past that the
simple
half wave dipole WAS a prefect example of equilibrium! NOW it
isn't???
have you had a new revelation while i had your old email address
plonked??

David,
You admit to not understanding the term "equilibrium" so what do you
care what I say and in what content.
If you consider a half wave dipole as being in equilibrium you have to
consider the electrical circuit
consisting of a capacitance from the antenna to ground or the route
thru the center of of the radiator, both of thes circuits
can be considered as being in equilibrium. However, on this newsgroup
a fractional wavelength radiator is considered as an open circuit for
some reason and thus under those circumstances the half wave dipole is
not in equilibrium.
Now your views on radiation is all over the place so it is very hard
for me to determine the context of what you say.
Art

Long before we rode our dinosaurs to club meetings the bright lights
had completely agreed that the strength of radio signals at far off
places was a function of the integral of i·dl where dl is the bigness
of the aerial. Maybe it's in Sears and Zemansky. I dunno . . nor do I
really care.

w3rv

Antennas for All Applications, 3rd Edition, Kraus & Marhefka, McGraw-Hill,
page 12.

Begin quote

Regardless of antenna type, all involve the same basic principle that
radiation is produced by accelerated (or decelerated) charge. The basic
equation of radiation may be expressed simply as

IL = Qv (A m / s)

where

I = time-changing current, A/s
L = length of current element, m
Q = charge, C
v = time change of velocity which equals the acceleration of the charge,
m/s

Thus, time-changing current radiates and accelerated charge radiates. For
steady-state harmonic variation, we usually focus on current. For
transients
or pulses, we focus on charge. The radiation is perpendicular to the
acceleration, and the radiated power is proportional to the square of IL
or
Qv.

end quote

Cheers,
John

John
If Kraus said "The radiation is perpendicular to the accelleration"
then the book is worthless.
Review the scalar quantities of a radiator. It is impossible for the
resultant to be at 90
degrees to the antenna axis. I suspect the roots of this untruth was
the invention of the
planar antenna. For maximum horizontal radiation a radiator will be
around 10 degrees
out of parallel to the earth surface, not parallel.
The king is dead, long live the king. Old books just cannot keep up to
date
Regards
Art
ie the yagi

Art -

I was actually replying to W3RV. However, since you piped up...

Have you had any books on the subject published? How about research papers?
Anything published at all? Do you have any presentations with equations
prepared to support your claim? To which companies have you sold your
expertise in this field? Have your taught any classes?

It is laughable to think anybody would consider you an authority on the
subject, much less a greater authority than Kraus or any other contributor
to this group. You really should get some psychiatric help to quell those
delusions of grandeur you have.

Cheers,
John

Let's keep to the subject and put the other comments aside.
Do you have any antenna computor programs that you have confidence in?
What are they so I can give you thr figures to prove it to yourself
Art

By the way John, read the book and determine why he points to a pitch
angle for best results
Thus pitch angle is not at right angles so perhaps you can explain
that. You can't learn just by belittling facts
Art