Antenna gain question
 

Cecil Moore wrote:

Jim Kelley wrote:

i.e. what Roy said. But I think there's still more to it. I tried to
give the other Richard a hint about it but it didn't resonate.


Then obviously your XC didn't equal your XL.

Probably just a difference in wavelength.

ac6xg

Antenna gain question
 

On Fri, 04 Nov 2005 11:42:43 -0800, Jim Kelley
wrote:
This would be a
given seeing that the parasitic elements would be virtually invisible,
rendering the "driven" element un-differentiable from the simple
dipole.

i.e. what Roy said.

On Wed, 02 Nov 2005 00:11:09 -0800, Roy Lewallen among many things wrote:

I have to admit, I was looking at this a[s] more of a problem of equal
signals arriving from all directions

Hi Jim,

I also approached the problem the same way, this is in glaring
contrast to what I've written in the past two posts which are vastly
divergent from this sense of "equal signals."

As I originally presented data from the model of "equal signals
arriving from all directions" it presented that a dipole's response
was separable from that of a yagi, and showed more response which
contradicts some correspondents, and aligns with others.

Such an outcome stands to reason, the yagi cannot see all sources, the
dipole can. If I illuminated the yagi from each source in turn (all
others off) and correlated the response to the source's angle, the
composite would simply reveal the characteristic yagi response lobe
and the sum of those powers MUST fall below the total power available
to the dipole.

The one over-riding difference between all these scenarios and the
expectations of the yagi is that the yagi is not illuminated with a
plane field, but with a radial field. The composite front of many
sources presents a complex antenna (the yagi) with the appearance of a
wave of extremely high curvature impinging upon it. The mechanics of
gain/directivity are not going to function in the same manner to that
yagi for both fashions of applying the power. Hence the yagi fails to
exhibit a higher response than the simple dipole.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Richard Clark wrote:

On Fri, 04 Nov 2005 11:42:43 -0800, Jim Kelley
wrote:

This would be a
given seeing that the parasitic elements would be virtually invisible,
rendering the "driven" element un-differentiable from the simple
dipole.

i.e. what Roy said.


On Wed, 02 Nov 2005 00:11:09 -0800, Roy Lewallen among many things wrote:


I have to admit, I was looking at this a[s] more of a problem of equal
signals arriving from all directions


Hi Jim,

I also approached the problem the same way, this is in glaring
contrast to what I've written in the past two posts which are vastly
divergent from this sense of "equal signals."

As I originally presented data from the model of "equal signals
arriving from all directions" it presented that a dipole's response
was separable from that of a yagi, and showed more response which
contradicts some correspondents, and aligns with others.

Such an outcome stands to reason, the yagi cannot see all sources, the
dipole can. If I illuminated the yagi from each source in turn (all
others off) and correlated the response to the source's angle, the
composite would simply reveal the characteristic yagi response lobe
and the sum of those powers MUST fall below the total power available
to the dipole.

The one over-riding difference between all these scenarios and the
expectations of the yagi is that the yagi is not illuminated with a
plane field, but with a radial field. The composite front of many
sources presents a complex antenna (the yagi) with the appearance of a
wave of extremely high curvature impinging upon it. The mechanics of
gain/directivity are not going to function in the same manner to that
yagi for both fashions of applying the power. Hence the yagi fails to
exhibit a higher response than the simple dipole.

73's
Richard Clark, KB7QHC

Let me thank you again for the work you've put in on this. The thing
is, the idea of squeezing a dipole field pattern into the shape of a
Yagi pattern for example, pretty much dictates that with the proper
field geometry, we should be able to realize equal amounts of energy in
both antennas. I think that's the correct answer. I'm just trying to
see a way to get to it. Another approach might be to integrate the
results from a large number of point sources.

73, AC6XG

Antenna gain question
 

Richard Clark wrote:
. . .
Such an outcome stands to reason, the yagi cannot see all sources, the
dipole can. If I illuminated the yagi from each source in turn (all
others off) and correlated the response to the source's angle, the
composite would simply reveal the characteristic yagi response lobe
and the sum of those powers MUST fall below the total power available
to the dipole.


Yet if you provide the same power to the dipole and the Yagi and
integrate the total field from each, the total field powers from both
are the same.

So is reciprocity invalid?

Roy Lewallen, W7EL

Antenna gain question
 

On Fri, 04 Nov 2005 15:45:39 -0800, Roy Lewallen
wrote:

Richard Clark wrote:
. . .
Such an outcome stands to reason, the yagi cannot see all sources, the
dipole can. If I illuminated the yagi from each source in turn (all
others off) and correlated the response to the source's angle, the
composite would simply reveal the characteristic yagi response lobe
and the sum of those powers MUST fall below the total power available
to the dipole.


Yet if you provide the same power to the dipole and the Yagi and
integrate the total field from each, the total field powers from both
are the same.

So is reciprocity invalid?

Hi Roy,

No, the presumption:
that this specific problem supports that reciprocity
is invalid.

Feel free to exhibit that the sum of powers, from identical remote
sources, located in a locus of points equidistant from a given point,
applied to
1. a dipole;
2. a yagi
demonstrate identically recovered power.

This is not the same as applying the same power to both and
integrating at a locus of points equidistant from a given point.

I could, of course, be wrong. I will investigate further if you have
any constructive suggestions such as Jim offered. I think it would be
instructive to be able to confirm it through available tools.

73's
Richard Clark, KB7QHC

Antenna gain question
 

On Wed, 02 Nov 2005 22:27:45 -0800, Richard Clark
wrote:

On Fri, 28 Oct 2005 20:37:07 GMT, Ron wrote:

Assume an incoming rf signal has exactly the same strength in all 3
dimensions i.e., completely omnidirectional. Question: would an
antenna having gain capture any more signal power than a completely
omnidirectional antenna with no gain?

Hi All,

Well, it is time to discard the speculation and let modeling approach
this for an answer that at least offers more than swag.

First we strip away the sphere and solve this in two dimensions. To
do that we simply construct a ring of sources surrounding the
prospective antennas and let the winning design emerge.

EZNEC+ ver. 4.0

Dipole in Ring of Sources 11/2/2005 10:00:48 PM

--------------- LOAD DATA ---------------

Frequency = 70 MHz

Load 1 Voltage = 4.783 V. at 23.52 deg.
Current = 0.06643 A. at 23.52 deg.
Impedance = 72 + J 0 ohms
Power = 0.3177 watts

Total applied power = 2000 watts

Total load power = 0.3177 watts

Taking the determination above as the "standard" I then have
progressed to place an NBS yagi in three space about the center to
obtain its best result.

All such expressions (x,y,z) of the placement of the NBS yagi are with
respect to its "driven" element.

0,0,0 Power = 0.2091 watts
..5,0,0 Power = 0.2198 watts
1,0,0 Power = 0.1429 watts
1.5,0,0 Power = 0.1026 watts
2,0,0 Power = 0.1601 watts
2.5,0,0 Power = 0.2113 watts
3,0,0 Power = 0.1571 watts
3.5,0,0 Power = 0.06028 watts
4,0,0 Power = 0.04128 watts

So, within one quadrant, and over the space of roughly a wavelength,
and at intervals of roughly one eighth wavelength, nothing emerges as
being equal to the "standard" above. Except perhaps a hidden peak
between 0,0,0 and .5,0,0. To investigate this:
..25,0,0 Power = 0.2286 watts
examining further:
..125,0,0 Power = 0.2219 watts
nope, examining further:
..375,0,0 Power = 0.2278 watts
nope, examining further:
..30,0,0 Power = 0.2291 watts
nope, examining further:
..35,0,0 Power = 0.2285 watts
nope, looks like the one before at .30,0,0 is the new sweet spot.

Now, to proceed to investigate the other quadrants to see if there is
symmetry:
-3.5,0,0 Power = 0.03997 watts
0,3.5,0 Power = 0.005925 watts
0,-3.5,0 Power = 0.005859 watts

This last offers that on the Y axis there is a strong symmetry, and
along the X axis there is a moderate symmetry. Now, in regard to both
the X and the Y axis, there is a moderate symmetry. If we were to
look at the fine data attempting to find the peak, we should notice
that the "center" of the antenna lies between the "driven" element and
its reflector. My having chosen the "driven" element as the nominal
center was in error and my guess is that if I re-visited the same
quadrant test above, with that new center at the sweet spot, then we
would find very strong symmetry in all four quadrants. I will add
that the Y axis data supports this due to its strong symmetry that is
relatively immune from the choice of antenna center - at least at this
scale.

Putting that aside, it is enough to suggest that barring an
exquisitely positioned peak of rather a sharp rise, then the yagi
exhibits a poorer response compared to a dipole of approx. 1.4dB.

Others are encouraged to investigate further to reclaim that missing
dB or to put the horns to my error.

73's
Richard Clark, KB7QHC

Antenna gain question
 

On Fri, 04 Nov 2005 15:39:18 -0800, Jim Kelley
wrote:

Another approach might be to integrate the
results from a large number of point sources.

Hi Jim,

I just did that - literally.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Dear friends:

Reciprocity principle it is not violated in this situation but... which
are the antennas?,

Let us feed a directional antenna that emits a hypothetical conical
beam = 1 sr, pointed toward north pole of the inner surface of the
sphere, for example. The radiant intensity or radiometric flow for
unit of solid angle in the area illuminated by the antenna, will be 1
W/sr, ok?.

If that same portion of the imaginary sphere receive from outer space,
an energy convergent flow on the same previously illuminated area for
the beam with a density = 1 W/sr, naturally the directional antenna
would be able to pick up it entirely, the principle of reciprocity is
respected (not violated?)

Now we make the same thing with a isotropic radiator (same power = 1
W).
The energy density that crosses the sphere's surface going out, now is
1 W / (4*pi) sr, ok?.

If for that surface, comes from the outer side, energy with that same
density and we pick up it with the same isotropic antenna we obtain one
watt, truth again? (and the principle of reciprocity would be ok )

Now let us suppose that same energy density 1/(4*Pi) W, received from
the whole surface of the sphere.

Let us reinstall the directional antenna instead of the isotropìc one.


How much energy it will be able to pick up 1 watt? or 1 / 4*Pi watt?

(could 1 W be picked up if the directive antenna only "see" an sphere's
area corresponding to 1 sr?)

Perhaps, the problem would not be on the reciprocity principle but in
the way of applying it to this example.


If instead of outlining the problem with antennas and radio signals,
the friend had outlined it with another energy form, luminous, for
example, and instead of antennas it had proposed light reflectors,
would the answers be the same ones?

I believe that it is legítimate (rightfull?) to associate this problem
with related phenomenon of radiant energy flow in general.

I also believe that the analogy between directional antennas and a
luminous reflectors it is applicable, otherwise we would be to a step
of violating the conservation of the energy principle... :)

Puf...!, I hope I`ll be able to translate this...

73's of Miguel Ghezzi (LU 6ETJ)
------------------------------------------------------------------------

El principio de reciprocidad se cumple en esta situación pero...
¿cuales son las antenas?,

Alimentemos una antena direccional que emita un haz conico hipotetico
de 1 sr, apuntada hacia el polo norte de la superficie interior de la
esfera, por ejemplo. La intensidad radiante o flujo radiometrico por
unidad de ángulo solido en la zona iluminada por la antena, sera 1
W/sr, ok?.

Si esa misma porcion de la esfera imaginaria recibiera desde exterior
un flujo de energia convergente sobre la misma area anteriormente
iluminada por el haz con una densidad = 1 W/sr, naturalmente la antena
direccional seria capaz de recogerla integramente, el principio de
reciprocidad se cumple...

Ahora hacemos lo mismo con un radiador isotropico (la misma potencia, 1
W).
La densidad de energia que atraviesa la superficie interior de la
esfera ahora es 1 W/(4*pi) sr, ok?. Si por esa superficie pasara,
procedente del exterior, energía con esa misma densidad y la
recogieramos con la misma antena isotropica volveriamos a obtener un
watt ¿verdad? (y el principio de reciprocidad continuaria
cumpliendose...)

Supongamos ahora esa misma densidad de energía 1/(4*Pi) W, recibida
desde fuera por toda la superficie de la esfera.

Reinstalemos la antena direccional en lugar de la isotrópica,

Cuanta es la energía podra ella recoger 1 watt? or 1/ 4*Pi watt?

(¿acaso podria recoger 1 W si solo "puede ver" una zona de la esfera
de 1 sr?)

Tal vez, el problema no estaria en el principio de reciprocidad sino en
la manera de aplicarlo a este ejemplo.

Si en vez de plantear el problema con antenas y señales de radio, el
amigo lo hubiera planteado con otra forma de energia,
luminosa, por ejemplo, y en vez de antenas hubiera propuesto
reflectores de luz, las respuestas serian las mismas?

Yo creo que es legitimo asociar este problema con los fénómenos
relacionados con el flujo de energía radiante en general.

Tambien creo que la analogia entre una antena direccional y un
reflector es aplicable, de lo contrario estariamos a un paso de violar
el principio de conservación de la energía... :)

Puf...! espero poder traducir esto bien...

73's de Miguel Ghezzi (LU 6ETJ)

Antenna gain question
 

Richard Clark wrote:
Others are encouraged to investigate further to reclaim that missing
dB or to put the horns to my error.

Of course, you have deviated considerably from the original
infinite number of coherent sources.
--
73, Cecil http://www.qsl.net/w5dxp

Antenna gain question
 

"Cecil Moore" wrote
Of course, you have deviated considerably from the original
infinite number of coherent sources.

================================

You guys sure know how to enjoy yourselves trying to analyse
hypothetical situations.

Without any loss in precision, just imagine an isotropic receiver
surrounded by 6 equal intensity beams focussed upon it. Forget all
about an infinite number of radiators.

Or, better still, forget all about the original exceedingly
ill-defined question by a leg-puller. You have been trolled. You
should be ashamed of yourselves for being taken in by such a question.

By the way, the subject of "antenna gains" is amongst the most
confusing of all old-wives' tales. It's worse than so-called VSWR
measurements on non-existent transmission lines. Or from which ends,
or the middle bit, of a dipole does the radiation occur.
----
Reg.

Antenna gain question
 

On Sat, 5 Nov 2005 18:15:30 +0000 (UTC), "Reg Edwards"
wrote:
"Cecil Moore" wrote
Of course, you have deviated considerably from the original
infinite number of coherent sources.
You guys sure know how to enjoy yourselves trying to analyse
hypothetical situations.

So now there are at least two of you who can't find the "missing"
power. Kelvinator is winding up a pitch to bounce another piece of
chalk off your noggin, Reg. Fumbling what-ifs and nary a number from
anyone.
"WORK?!?" [with apologies to Maynard G. (for Walter) Krebs, rip].

Antenna gain question
 

Or, better still, forget all about the original exceedingly
ill-defined question by a leg-puller. You have been trolled. You
should be ashamed of yourselves for being taken in by such a question.

Hello Reg,

I wrote the original question. It may be dumb but it was not
facetious. I am not a troll.

Happy birthday,

Ron, W4TQT

Antenna gain question
 

Richard Clark wrote:

EZNEC+ ver. 4.0

Dipole in Ring of Sources 11/2/2005 10:00:48 PM

--------------- LOAD DATA ---------------

Frequency = 70 MHz

Load 1 Voltage = 4.783 V. at 23.52 deg.
Current = 0.06643 A. at 23.52 deg.
Impedance = 72 + J 0 ohms
Power = 0.3177 watts

Total applied power = 2000 watts

Total load power = 0.3177 watts


Taking the determination above as the "standard" I then have
progressed to place an NBS yagi in three space about the center to
obtain its best result.

All such expressions (x,y,z) of the placement of the NBS yagi are with
respect to its "driven" element.

0,0,0 Power = 0.2091 watts
.5,0,0 Power = 0.2198 watts
1,0,0 Power = 0.1429 watts
1.5,0,0 Power = 0.1026 watts
2,0,0 Power = 0.1601 watts
2.5,0,0 Power = 0.2113 watts
3,0,0 Power = 0.1571 watts
3.5,0,0 Power = 0.06028 watts
4,0,0 Power = 0.04128 watts

So, within one quadrant, and over the space of roughly a wavelength,
and at intervals of roughly one eighth wavelength, nothing emerges as
being equal to the "standard" above. Except perhaps a hidden peak
between 0,0,0 and .5,0,0. To investigate this:
.25,0,0 Power = 0.2286 watts
examining further:
.125,0,0 Power = 0.2219 watts
nope, examining further:
.375,0,0 Power = 0.2278 watts
nope, examining further:
.30,0,0 Power = 0.2291 watts
nope, examining further:
.35,0,0 Power = 0.2285 watts
nope, looks like the one before at .30,0,0 is the new sweet spot.

Now, to proceed to investigate the other quadrants to see if there is
symmetry:
-3.5,0,0 Power = 0.03997 watts
0,3.5,0 Power = 0.005925 watts
0,-3.5,0 Power = 0.005859 watts

This last offers that on the Y axis there is a strong symmetry, and
along the X axis there is a moderate symmetry. Now, in regard to both
the X and the Y axis, there is a moderate symmetry. If we were to
look at the fine data attempting to find the peak, we should notice
that the "center" of the antenna lies between the "driven" element and
its reflector. My having chosen the "driven" element as the nominal
center was in error and my guess is that if I re-visited the same
quadrant test above, with that new center at the sweet spot, then we
would find very strong symmetry in all four quadrants. I will add
that the Y axis data supports this due to its strong symmetry that is
relatively immune from the choice of antenna center - at least at this
scale.

Putting that aside, it is enough to suggest that barring an
exquisitely positioned peak of rather a sharp rise, then the yagi
exhibits a poorer response compared to a dipole of approx. 1.4dB.

Others are encouraged to investigate further to reclaim that missing
dB or to put the horns to my error.

73's
Richard Clark, KB7QHC

Hi Richard,

I think what you're seeing is the 3-D interference pattern generated by
your sources. I'm not sure that really tells us very much about the
antennas themselves. You'd need to surround each of the antennas with a
uniform field in order to compare them. By uniform, I mean the field
intensity toward the antenna is the same in any direction.

Thanks, AC6XG

Antenna gain question
 

Jim Kelley wrote:
I think what you're seeing is the 3-D interference pattern generated by
your sources.

Richard is not trying to superpose powers again, is he? :-)
--
73, Cecil http://www.qsl.net/w5dxp

Antenna gain question
 

Jim Kelley wrote:

Hi Richard,

I think what you're seeing is the 3-D interference pattern generated by
your sources. I'm not sure that really tells us very much about the
antennas themselves. You'd need to surround each of the antennas with a
uniform field in order to compare them. By uniform, I mean the field
intensity toward the antenna is the same in any direction.

How about polarization?

Roy Lewallen, W7EL

Antenna gain question
 

Roy Lewallen wrote:

Jim Kelley wrote:


Hi Richard,

I think what you're seeing is the 3-D interference pattern generated
by your sources. I'm not sure that really tells us very much about
the antennas themselves. You'd need to surround each of the antennas
with a uniform field in order to compare them. By uniform, I mean the
field intensity toward the antenna is the same in any direction.


How about polarization?

Roy Lewallen, W7EL

Hi Roy,

Your guess is better than mine. I think in order not to bias the
results, the solution would have to be that each source is randomly
polarized, i.e. the Sun redshifted down into the radio spectrum - coming
from every direction. The ring of point sources is an interesting
approach. One could use rings at some number of elevation angles, both
above and below the plane of the antennas. The greater the elevation
angle, the smaller the diameter of the ring such that the radial
distance to the antenna is kept constant. But I imgaine you have ideas
of your own in this regard.

73, ac6xg

Antenna gain question
 

See comment below.
--
J. Mc Laughlin; Michigan U.S.A.
Home:

"Richard Harrison" wrote in message
...
Jim Kelley, AC6XG wrote:
snip

To a first approximation
though, we assume that all the parallel rays intercepted by a dish are
focused on the radiator and aid, adding in-phase. Received carrier power
excites the antenna and this causes a minimum of 50% of this power to be
re-radiated if the antenna is perfectly matched to to the receiver load.
The antenna`s radiation resistance in this case becomes the Thevenin`s
source resistance for the receiver load on the antenna. This requires a
conjugate match between the antenna and receiver input impedances.

----- ... not if one wishes to maximize SNR. Best SNR requires a (slight)
mismatch. Of course, this issue is only significant if SNR is due to the
noise figure (NF) of the receiver and the SNR is small.
73 Mac N8TT

Antenna gain question
 

On Mon, 07 Nov 2005 11:16:08 -0800, Jim Kelley
wrote:

I think what you're seeing is the 3-D interference pattern generated by
your sources.

Hi Jim,

3D in two-space? No.

I'm not sure that really tells us very much about the antennas themselves.
You'd need to surround each of the antennas with a
uniform field in order to compare them. By uniform, I mean the field
intensity toward the antenna is the same in any direction.

The problem has symmetry on its side, additional source add to the
dipole in equal measure to the yagi. Adding more power does not
create the missing power already lost.

73's
Richard Clark, KB7QHC

Antenna gain question
 

On Mon, 07 Nov 2005 15:08:26 -0800, Roy Lewallen
wrote:

How about polarization?

Hi Roy,

How about it?

73's
Richard Clark, KB7QHC

Antenna gain question
 

On Mon, 07 Nov 2005 15:40:58 -0800, Jim Kelley
wrote:

One could use rings at some number of elevation angles

Hi Jim,

This would increase the tedium factor considerably. Simply rotate the
ring.

73's
Richard Clark, KB7QHC

Antenna gain question
 

On Mon, 07 Nov 2005 15:40:58 -0800, Jim Kelley
wrote:

the solution would have to be that each source is randomly polarized

Hi Jim,

I have worked further with the "random" applications. "Random" is no
simple thing as published data has already revealed and my additions,
editions, and refinements have not bought much more traction. Putting
enough decimal places into the "random" valuations would be
mind-numbingly brutal; and as interesting as it would be, it would be
a solution in search of a different problem.

If "random" put oil on troubled waters and reduced the 1.4dB
discrepancy to say 0.4dB, it says nothing of the original 1dB. And
all these machinations to fill the sky with sources so they can look
over the reflector of the yagi.... If you pour more water into the
bucket, you will eventually fill it, but it won't tell you why the
bucket leaks.

However, it is nice to see that the topic still has legs.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Richard Clark wrote:

On Mon, 07 Nov 2005 11:16:08 -0800, Jim Kelley
wrote:


I think what you're seeing is the 3-D interference pattern generated by
your sources.


Hi Jim,

3D in two-space? No.

It was you who claimed to have modeled the antenna in three-space, was
it not? Either way, in three-space or two, you have an interference
pattern. That is the point.

I'm not sure that really tells us very much about the antennas themselves.
You'd need to surround each of the antennas with a
uniform field in order to compare them. By uniform, I mean the field
intensity toward the antenna is the same in any direction.


The problem has symmetry on its side, additional source add to the
dipole in equal measure to the yagi. Adding more power does not
create the missing power already lost.

It would be silly to expect it to. How much power should you expect to
measure with your instruments positioned in an interference null? This
is the nature of your "leaky bucket".

73, ac6xg

Antenna gain question
 

Jim Kelley wrote:

Richard Clark wrote:
3D in two-space? No.

It was you who claimed to have modeled the antenna in three-space, was
it not?

Actually, if time appeared in the equations as in 2*pi*f*t,
then it would be 3Dspace+1Dtime = 4D, no?
--
73, Cecil http://www.qsl.net/w5dxp

Antenna gain question
 

On Tue, 08 Nov 2005 11:08:00 -0800, Jim Kelley
wrote:

Hi Jim,

Either way, in three-space or two, you have an interference
pattern. That is the point.

The point being what? The observation of the pattern is simply that,
an observation. That a pattern exists is also hardly a revolutionary
concept. That it is the product of many sources does not preclude the
results as physics allows a wave to be viewed as a continuum of
sources along its length.

The problem has symmetry on its side, additional source add to the
dipole in equal measure to the yagi. Adding more power does not
create the missing power already lost.

It would be silly to expect it to. How much power should you expect to
measure with your instruments positioned in an interference null? This
is the nature of your "leaky bucket".

When two designs inhabit the same null, as you put it (which is a
mistaken attribution because there are regions with two orders
magnitude less power resolved by the same designs), and one exhibits
more response than the other (regardless of its subsequent
repositioning and that was performed to the degree of 1/80th wave
increments); then it stands to reason one design is inferior to the
other in the capture of a continuum of radiation encompassing them.

This is all displayed in the data offered.

The yagi is that inferior design. This leaky bucket is not fixed by
placing it outside of the "null" (ironically it was very near in a
peak); hence an interference pattern is immaterial to the loss of
power as both designs suffer the same pattern - and equally I might
point out, if other arguments are consistently applied that equal
powers should be exhibited.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Richard Clark wrote:

On Tue, 08 Nov 2005 11:08:00 -0800, Jim Kelley
wrote:

Hi Jim,


Either way, in three-space or two, you have an interference
pattern. That is the point.


The point being what? The observation of the pattern is simply that,
an observation. That a pattern exists is also hardly a revolutionary
concept. That it is the product of many sources does not preclude the
results as physics allows a wave to be viewed as a continuum of
sources along its length.

The typical radiation pattern which would ordinarily illuminate an
antenna does not have an array of 'holes' in it - symmetrical or
otherwise. Further, you can't expect to compare the performance of two
different antennas when the field you're exposing them to is malformed
and non-uniform. The result would be convoluted (as you have shown).

This leaky bucket is not fixed by
placing it outside of the "null" (ironically it was very near in a
peak);

It is fixed by creating a uniform field. As I said before, integrating
the results from a large number of individual point sources (rather than
superposing the fields from a large array of point sources) would not
produce an interference pattern.

hence an interference pattern is immaterial to the loss of
power as both designs suffer the same pattern - and equally I might
point out, if other arguments are consistently applied that equal
powers should be exhibited.

This is apparently incorrect, as both antennas should produce the same
result.

One wouldn't have to do as much handwaving and fast talking if the field
was uniform, Richard.

73, ac6xg

Antenna gain question
 

On Tue, 08 Nov 2005 16:13:34 -0800, Jim Kelley
wrote:

It is fixed by creating a uniform field. As I said before, integrating
the results from a large number of individual point sources (rather than
superposing the fields from a large array of point sources) would not
produce an interference pattern.

Hi Jim,

Here you are clearly wrong in some presumption. For one, I have done
exactly as you have demanded should be done and you find an error. I
have responded several times to this identical complaint you've
offered, and you have neither offered what that error is, or where I
differ from what you insist in integrating the results. It seems to
me in performing it exactly as you describe it, that I have very
little choice in that matter anyway and barring further elaboration in
how my fulfilling your imperative differs from your imperative, your
point remains rather elusive.

hence an interference pattern is immaterial to the loss of
power as both designs suffer the same pattern - and equally I might
point out, if other arguments are consistently applied that equal
powers should be exhibited.

This is apparently incorrect, as both antennas should produce the same
result.

"Should" is the operative word here. "Doesn't" is clearly exhibited.
You don't explain the "Should" and you clearly have issue with the
"Doesn't," but to this point you and others haven't got much to offer.
As I put the challenge to Roy, offer your own model that fulfills the
"Should." Results haven't exactly flown out of that yet, if ever.

One wouldn't have to do as much handwaving and fast talking if the field
was uniform, Richard.

A circular uniform field? And one that exists without a pattern of
interference within it? That could only exist at the beginning of
creation reverse filling the void of the cosmos.
THIS is hand waving. ;-)

However, let's just cut to the chase in that you are clearly disturbed
by this "interference pattern" that the tool so clearly reveals. What
about it is so inimical to your expectations? The partitioning of the
problem into multiple sources dates back to Huygens' principle.
Predating EZNEC by 300+ years suggests that the math has more or less
stabilized such that the model confirms it.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Richard Clark wrote:
On Tue, 08 Nov 2005 16:13:34 -0800, Jim Kelley
wrote:


It is fixed by creating a uniform field. As I said before, integrating
the results from a large number of individual point sources (rather than
superposing the fields from a large array of point sources) would not
produce an interference pattern.


Hi Jim,

Here you are clearly wrong in some presumption. For one, I have done
exactly as you have demanded should be done and you find an error. I
have responded several times to this identical complaint you've
offered, and you have neither offered what that error is, or where I
differ from what you insist in integrating the results. It seems to
me in performing it exactly as you describe it, that I have very
little choice in that matter anyway and barring further elaboration in
how my fulfilling your imperative differs from your imperative, your
point remains rather elusive.

You forgot to write - Harumph! ;-)

If you'll read back, you'll find that the descriptions you've provided
of your model are far less than effusive and illuminating. No more than
a few partial or incomprehensible sentences were provided. We're left
to guess most of the details of what you have done. I can only deduce
some of it from the results you have provided. I made no criticism of
this. You spoke of symmetries and lost power without mention of their
nature. So I mentioned their nature. It should have been obvious, but
you hadn't even alluded to a possible explanation for this "lost power".

BTW, single sources do not produce interference patterns (unless somehow
you're inadvertantly causing diffraction somewhere between the source
and the antenna). Each individual source will provide a signal. The
amplitude and phase of the signal rendered in the antenna from a single
source will depend the position of the source relative to the
orientation and construction of the antenna. Summing all the individual
signals rendered in the antenna from a multitude of individuals sources
does not create an interference pattern in 3 space. It produces a
simple magnitude and phase which would hypothetically appear in the
antenna if an incoming uniform 'spherical field' existed.

However, let's just cut to the chase in that you are clearly disturbed
by this "interference pattern" that the tool so clearly reveals.

I don't find interference to be disturbing. I'm simply pointing out
that we shouldn't expect textbook results from antennas that are
positioned amidst interfering sources. I'm sorry to have perturbed you
with my comments and observations. Any criticisms you may have
precieved should have been taken as purely constructive to the task.
That is my only intent.

73, ac6xg

Antenna gain question
 

On Wed, 09 Nov 2005 12:31:31 -0800, Jim Kelley
wrote:
If you'll read back, you'll find that the descriptions you've provided
of your model are far less than effusive and illuminating.

Hi Jim,

Is that the standard we now measure by? The data is not going to
change and its repetition is not necessary. Do you have something new
to point out?

You spoke of symmetries and lost power without mention of their nature.

I left speculation to others and you stepped up to the podium.

So I mentioned their nature. It should have been obvious, but
you hadn't even alluded to a possible explanation for this "lost power".

Again, this was already offered by me - I may have made a mistake. As
of yet, no one seems interested in pursuing that. Other explanations
would hardly qualify as such, they would be speculations as I've said
and given there is no competing model supporting those speculations -
well, the adage that talk is cheap has had the price slashed by
posting is cheaper.

BTW, single sources

Demonstrate a single source that offers an inward radiating circular
field. I can anticipate you might be tempted to suggest the
multiplicity of sources accruing from the big bang, but then that
would violate your premise:

do not produce interference patterns

As I've suggested, all it takes is a positive model supporting a
negation of my results.

However, let's just cut to the chase in that you are clearly disturbed
by this "interference pattern" that the tool so clearly reveals.

I don't find interference to be disturbing. I'm simply pointing out
that we shouldn't expect textbook results from antennas that are
positioned amidst interfering sources.

Well, then it descends to a population of one disturbed correspondent,
and Roy has yet to resolve his conflict. Your last observation must
emphasize it if we cannot expect a modeler to provide textbook
results.

So, as it stands I see that no one has a competing model and the data
remains an enigma to most.

73's
Richard Clark, KB7QHC

Antenna gain question
 

Jim Kelley wrote:
Any criticisms you may have
precieved should have been taken as purely constructive to the task.

Richard probably considers you input to be constructive interference. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Antenna gain question
 

Cecil Moore wrote:
Jim Kelley wrote:

Any criticisms you may have precieved should have been taken as purely
constructive to the task.


Richard probably considers your input to be constructive interference. :-)

Then it wasn't for naught. We've finally landed upon something that you
and Richard can agree upon. ;-)

73, Jim AC6XG