On Thu, 3 Sep 2009 19:11:42 -0700 (PDT), wrote:

How in the heck are you going to
get **ANY** vertical radiator to have a truly isotropic pattern?
It's impossible. An isotropic pattern is a theoretical pattern
in which radiation is equal in all directions. Such a pattern
does not exist with real antennas.

A real isotropic radiator may not exist, but one can get fairly close.
If you believe the model, the total error is 0.44 db. See:
http://802.11junk.com/jeffl/antennas/isotropic/index.html
The NEC2 deck is under the photo labeled "main".

I once built one of these antennas on roughly 444MHz out of cardboard
and magnet wire. The oscillator was a small crystal can oscillator
running from a 9V battery to avoid having the feed coax wrecking the
pattern. The impedance was nowhere near 50 ohms and required a bit of
matching to get the VSWR down. I'm now digging for the photos.

I used a piece of string to maintain a constant radius, a tiny pickup
loop at the end of a length of coax cable running inline with the
string, and eventually going to my antique HP spectrum analyzer. On
the 2dB/div scale, it was a fairly good approximation of an isotropic
radiator with errors mostly caused by indoor reflections and
interference with the bench.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

Jeff Liebermann wrote:
On Thu, 3 Sep 2009 19:11:42 -0700 (PDT), wrote:

How in the heck are you going to
get **ANY** vertical radiator to have a truly isotropic pattern?
It's impossible. An isotropic pattern is a theoretical pattern
in which radiation is equal in all directions. Such a pattern
does not exist with real antennas.

A real isotropic radiator may not exist, but one can get fairly close.
If you believe the model, the total error is 0.44 db. See:
http://802.11junk.com/jeffl/antennas/isotropic/index.html
The NEC2 deck is under the photo labeled "main".

I once built one of these antennas on roughly 444MHz out of cardboard
and magnet wire. The oscillator was a small crystal can oscillator
running from a 9V battery to avoid having the feed coax wrecking the
pattern. The impedance was nowhere near 50 ohms and required a bit of
matching to get the VSWR down. I'm now digging for the photos.

I used a piece of string to maintain a constant radius, a tiny pickup
loop at the end of a length of coax cable running inline with the
string, and eventually going to my antique HP spectrum analyzer. On
the 2dB/div scale, it was a fairly good approximation of an isotropic
radiator with errors mostly caused by indoor reflections and
interference with the bench.



Nice. The 3d pic is impressive.

tom
K0TAR

On Sep 3, 10:29*pm, Jeff Liebermann wrote:
On Thu, 3 Sep 2009 19:11:42 -0700 (PDT), wrote:
How in the heck are you going to
get **ANY** vertical radiator to have a truly isotropic pattern?
It's impossible. An isotropic pattern is a theoretical pattern
in which radiation is equal in all directions. Such a pattern
does not exist with real antennas.

A real isotropic radiator may not exist, but one can get fairly close.
If you believe the model, the total error is 0.44 db. *See:
http://802.11junk.com/jeffl/antennas/isotropic/index.html
The NEC2 deck is under the photo labeled "main".

I once built one of these antennas on roughly 444MHz out of cardboard
and magnet wire. *The oscillator was a small crystal can oscillator
running from a 9V battery to avoid having the feed coax wrecking the
pattern. *The impedance was nowhere near 50 ohms and required a bit of
matching to get the VSWR down. *I'm now digging for the photos. *

I used a piece of string to maintain a constant radius, a tiny pickup
loop at the end of a length of coax cable running inline with the
string, and eventually going to my antique HP spectrum analyzer. *On
the 2dB/div scale, it was a fairly good approximation of an isotropic
radiator with errors mostly caused by indoor reflections and
interference with the bench. *

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
#http://802.11junk.com* * * * * * *
#http://www.LearnByDestroying.com* * * * * * * AE6KS

You cannot assume that one who makes an accusation has the status of
education to match his veracity. The person who stated that it is an
impossibility does not even posses a high school diploma. Climbing on
the back of his statements puts you back on the stage again!

On Sep 3, 6:14*pm, "Dave" wrote:
"Art Unwin" wrote in message

...

It seems that some do not understand what the Corriolis force is so
an find the here goes
When the Big Bang ocurred all energy was in *an arbitrary boundary

that's enough... the rest is just more blabbering. *first, spell it right,
its Coriolis with one r.
next, its not even a 'real' force, and is often called the Coriolis 'effect'
instead of force to make that clear. *and it is not linked to gravity, its
linked to rotation. *if the earth or any other body didn't rotate there
would be no Coriolis effect on it's surface and it would still have gravity.
I'm not even going to try to address the electro-weak babble, that is
totally non-sequitar.

David, you can find the famous "exclusion principle" by Wolfgang Pauli
in any
book on Quantum Mechanics. You should write a paper on where he weny
wrong based on your intuition. That gun you are firing is getting
lower and lower that I fear for your foot !

On Thu, 03 Sep 2009 23:01:30 -0500, tom wrote:

http://802.11junk.com/jeffl/antennas/isotropic/index.html

Nice. The 3d pic is impressive.
tom
K0TAR

Thanks, but the design is not mine. I think it came with a 4NEC2
samples collection, MiniNEC, or possibly with one of the other antenna
modeling packages. I've got them all muddled together so I can't
easily determine the source. I don't think I made any changes to the
model. Mostly, all I did was package the results into something
presentable on a web page. (Note: I tried to convince Ari to add a
web page creation feature to 4NEC2, but failed).

Incidentally, I has some illusion of using the isotropic approximation
antenna as a gain reference antenna. I know there are other reference
antenna designs that are more suitable, but I thought it would be an
interesting exercise. I also built one for 2.4GHz, which was a total
failure.

Drivel: Isotropic antenna patents:

"Spherical antennas having isotropic radiation patterns"
http://www.google.com/patents?id=--I2AAAAEBAJ

"Isotropic antenna system and notebook computer"
http://www.google.com/patents/about?id=M2UOAAAAEBAJ
Using multiple antennas to get a reasonably hemispherical pattern on a
laptop.

"Omnidirectional isotropic antenna"
http://www.google.com/patents?id=VQcYAAAAEBAJ
Uses a microwave lens fed by wavguide. Pattern is roughly
hemispherical.

"Near-isotropic low-profile microstrip radiator especially suited for
use as mobile vehicle antenna"
http://www.google.com/patents?id=wNE5AAAAEBAJ

"Near isotropic circularly polarized antenna"
http://www.google.com/patents?id=saMgAAAAEBAJ

etc.... plenty more found with a search for "isotropic antenna". Of
course, isotropic antennas don't really exist. Therefore all the
patents must be science fiction.

Incidentally, I'm still scratching my rapidly depilating head about
your answers to my question about antenna resonance. However, I wanna
do some more reading before demonstrating my ignorance on the subject
and making a fool of myself. Real-soon-now.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Thu, 3 Sep 2009 21:09:37 -0700 (PDT), Art Unwin
wrote:

You cannot assume that one who makes an accusation has the status of
education to match his veracity. The person who stated that it is an
impossibility does not even posses a high school diploma. Climbing on
the back of his statements puts you back on the stage again!

Hint: Please feel free to attack a persons ideas, logic, conclusions,
data, information, assertions, assumptions, pontifications, judgment,
and numbers. This is proper for a technical discussion. However,
attacking a persons background, education, personality, appearance,
and wallpaper is little better than a character assassination and
should be avoided. Discuss the ideas, not the person.

That being said, I've learned as much from those without the proper
credentials, than from those with the requisite degrees and
certifications. Hands on experience and Learn By Destroying(tm) are
amazingly good teachers.

Also, I judge people mostly by their willingness and ability to learn.
When learning stops, one rots in place and eventually withers. What
have you learned from this discussion on your Gaussian Radiative
Cluster?

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sep 3, 10:29*pm, Jeff Liebermann wrote:
On Thu, 3 Sep 2009 19:11:42 -0700 (PDT), wrote:
How in the heck are you going to
get **ANY** vertical radiator to have a truly isotropic pattern?
It's impossible. An isotropic pattern is a theoretical pattern
in which radiation is equal in all directions. Such a pattern
does not exist with real antennas.

A real isotropic radiator may not exist, but one can get fairly close.
If you believe the model, the total error is 0.44 db. *See:
http://802.11junk.com/jeffl/antennas/isotropic/index.html
The NEC2 deck is under the photo labeled "main".

I once built one of these antennas on roughly 444MHz out of cardboard
and magnet wire. *The oscillator was a small crystal can oscillator
running from a 9V battery to avoid having the feed coax wrecking the
pattern. *The impedance was nowhere near 50 ohms and required a bit of
matching to get the VSWR down. *I'm now digging for the photos. *

I used a piece of string to maintain a constant radius, a tiny pickup
loop at the end of a length of coax cable running inline with the
string, and eventually going to my antique HP spectrum analyzer. *On
the 2dB/div scale, it was a fairly good approximation of an isotropic
radiator with errors mostly caused by indoor reflections and
interference with the bench. *


Sure, you can get fairly close to isotropic with the right
system, but how are you going to do it by tipping a
vertical? The likely results do not fit my idea of isotropic.

U¿ytkownik napisa³ w wiadomo¶ci
...
On Sep 3, 10:29 pm, Jeff Liebermann wrote:
On Thu, 3 Sep 2009 19:11:42 -0700 (PDT), wrote:
How in the heck are you going to
get **ANY** vertical radiator to have a truly isotropic pattern?
It's impossible. An isotropic pattern is a theoretical pattern
in which radiation is equal in all directions. Such a pattern
does not exist with real antennas.

A real isotropic radiator may not exist, but one can get fairly close.
If you believe the model, the total error is 0.44 db. See:
http://802.11junk.com/jeffl/antennas/isotropic/index.html
The NEC2 deck is under the photo labeled "main".

I once built one of these antennas on roughly 444MHz out of cardboard
and magnet wire. The oscillator was a small crystal can oscillator
running from a 9V battery to avoid having the feed coax wrecking the
pattern. The impedance was nowhere near 50 ohms and required a bit of
matching to get the VSWR down. I'm now digging for the photos.

I used a piece of string to maintain a constant radius, a tiny pickup
loop at the end of a length of coax cable running inline with the
string, and eventually going to my antique HP spectrum analyzer. On
the 2dB/div scale, it was a fairly good approximation of an isotropic
radiator with errors mostly caused by indoor reflections and
interference with the bench.


Sure, you can get fairly close to isotropic with the right
system, but how are you going to do it by tipping a
vertical? The likely results do not fit my idea of isotropic.

"An isotropic radiator is a theoretical point source of waves which exhibits
the same magnitude or properties when measured in all directions".
The only way to make the real point source is the proper tipping. Of course
it must be a monopole.
S*

On Sep 3, 11:09 pm, Art Unwin wrote:


You cannot assume that one who makes an accusation has the status of
education to match his veracity. The person who stated that it is an
impossibility does not even posses a high school diploma. Climbing on
the back of his statements puts you back on the stage again!

Does not matter what education I started out with. They don't
teach antenna theory until college level anyway.
Being as you didn't take those courses in college either,
being a mechanical engineer, I don't see how you have any
real leg up on me at all as far as antenna theory.
You had to learn it on your own, same as I did.
You probably had a decent leg up in math at one time,
but you seem so senile now, I doubt it does you any good. :/
You don't seem to exercise the skill.. You hardly ever give out
any math to support any of your theories.

All of my antenna education has been self administered, and for all
you know, I might have eclipsed you years ago. You have no way of
really knowing unless someone gave us a test.
Heck, you went to college, and I was expelled from high school,
but as I general rule, I spell better than you do.
Not perfect, but I bet my rate of error is a good bit lower than
yours.

How do you explain that? And if that is the case, how can we be
sure that your lofty college education in mechanical engineering is
actually helping you to rise above that nasty ole dumbass NM5K
when it comes to antenna talk?

There are many here that know much more than I do, but as
far as I can tell, you ain't one of them. :/
You can telling a fetching yarn to reel em in, but when it comes to
producing the real goods, you vanish every time after a mind numbing
barrage of pure baffle gab.

Most of my antenna work is with real antennas in the real world.
I don't spend much time letting modeling programs run wild, and
then proclaim that the resulting designs they spit out require new
baffle gab theory to explain their operation.

So it's not really required that I be some rocket scientist here.
I'm not the one having to defend baffle gab.

But you on the other hand propose that you are going to rewrite the
books with your new theories.
And that most everyone here, except you of course, is a dribbling
idiot
not to swallow everything you say, hook, equilibrium, and weak force.
Being that is the case, I'd be a lot more worried about your education
than mine if I were you.
You are the one that needs to prove your case, not I.

wrote in message
...
On Sep 3, 11:09 pm, Art Unwin wrote:


You cannot assume that one who makes an accusation has the status of
education to match his veracity. The person who stated that it is an
impossibility does not even posses a high school diploma. Climbing on
the back of his statements puts you back on the stage again!

Does not matter what education I started out with. They don't
teach antenna theory until college level anyway.
Being as you didn't take those courses in college either,
being a mechanical engineer, I don't see how you have any
real leg up on me at all as far as antenna theory.
You had to learn it on your own, same as I did.
You probably had a decent leg up in math at one time,
but you seem so senile now, I doubt it does you any good. :/
You don't seem to exercise the skill.. You hardly ever give out
any math to support any of your theories.

All of my antenna education has been self administered, and for all
you know, I might have eclipsed you years ago. You have no way of
really knowing unless someone gave us a test.
Heck, you went to college, and I was expelled from high school,
but as I general rule, I spell better than you do.
Not perfect, but I bet my rate of error is a good bit lower than
yours.

How do you explain that? And if that is the case, how can we be
sure that your lofty college education in mechanical engineering is
actually helping you to rise above that nasty ole dumbass NM5K
when it comes to antenna talk?

There are many here that know much more than I do, but as
far as I can tell, you ain't one of them. :/
You can telling a fetching yarn to reel em in, but when it comes to
producing the real goods, you vanish every time after a mind numbing
barrage of pure baffle gab.

Most of my antenna work is with real antennas in the real world.
I don't spend much time letting modeling programs run wild, and
then proclaim that the resulting designs they spit out require new
baffle gab theory to explain their operation.

So it's not really required that I be some rocket scientist here.
I'm not the one having to defend baffle gab.

But you on the other hand propose that you are going to rewrite the
books with your new theories.
And that most everyone here, except you of course, is a dribbling
idiot
not to swallow everything you say, hook, equilibrium, and weak force.
Being that is the case, I'd be a lot more worried about your education
than mine if I were you.
You are the one that needs to prove your case, not I.

Well put.