RadioBanter - Antenna physical size

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Antenna physical size

On Mar 25, 1:31 pm, Cecil Moore wrote:
Richard Harrison wrote:
He who scoffs at Terman is at great peril.

If radiation was *only* perpendicular to the antenna,
wouldn't the beam width be fixed to the length of
the antenna? Wouldn't cloverleaf patterns be
impossible? What am I missing?
--
73, Cecil http://www.w5dxp.com

Cecil, he is not interested in finding the new,
he is more comfortable of staying with the old
people of his era. He doesn,t need proof and
doesn.t know how to handle it. Terman is the one thing left in life
he has, maybe we should leave him alone for eventual sainthood
ceremonies for Terman when they get to the milky way.
If he is looking for the Proof at the present time then we may
never hear from him again. No one has come to his aid with
a computor analysis realising that he is firmly set in his ways.
Heck, he won't even try our a computor and probably doesn't
have a new fangled television

Antenna physical size

Cecil Moore wrote:
"What am I missing?"

Radio waves spread during propagation. Huygens` principle is a cause.

Huygens says:
Each point on a primary wave front can be considered as a new source of
a secondary spherical wave and that a secondary spherical wave front can
be constructed as the envelope of these secondary waves. This is
illustrated in Fig. 5-37 on page 144 of the 3rd edition of Kraus`
"Antennas".

Best regards, Richard Harrison, KB5WZI

Antenna physical size

On Tue, 25 Mar 2008 12:43:49 -0700 (PDT), Art Unwin
wrote:

a new fangled television

TV as the hallmark of the new age?

More like a silver plated drool cup in the age of the Internet.

73's
Richard Clark, KB7QHC

Antenna physical size

Art Unwin wrote:
Cecil, he is not interested in finding the new,
he is more comfortable of staying with the old
people of his era.

I'm just trying to understand what Terman said.
Did he say that all of the radiation is perpendicular
to the radiating element or that most of the
radiation is perpendicular to the radiating element
or that none of the radiation is off the ends
of the element?
--
73, Cecil http://www.w5dxp.com

Antenna physical size

Richard Harrison wrote:
Cecil Moore wrote:
"What am I missing?"

Radio waves spread during propagation. Huygens` principle is a cause.

But the Method Of Moments used by NEC for antenna
radiation patterns calculates the interference at
a point in space based on radiation from different
elementary dipole sections of the antenna. For
instance, when the antenna is two wavelengths long
there is no more broadside radiation than there is
radiation off the ends.

In "Antenna Theory" by Balanis, in Chapter 8, page
407, on Moment Method, he illustrates the method
using radiation angles less than 45 degrees to
the radiating element.
--
73, Cecil http://www.w5dxp.com

Antenna physical size

Cecil Moore wrote:
"But the Method Of Moments used by NEC for antenna radiation patterns
calculates the interference at a point in space based on radiation from
different elementary dipole sections of the antenna."

Completely logical and it works. Interference or vector sum?

Terman illustrates radiation from an elementary doublet (dipole) , and
it is mostly at right angles to the antenna axis, on page 865 of his
1955 opus. On page 866 he shows an actual antenna consisting of numerous
elementary doublets and on page 867 he says:
"The result is that the fields radiated from different elementary
sections of a long wire add vectorially to give a sum that depends on
direction."

Kraus devotes Chapter 14 in the 3rd edition of "Antennas" to: "The
Cylindrical Antenna and the Moment Method (MM)."

Best regards, Richard Harrison, KB5WZI

Antenna physical size

I find this topic very interesting, including the mandrill part :)

We all want to have small, broadband, eficient antennas. I believe Art
is right in his original post, today we can have all these
characteristics in the same package. There is no law of physics
forbidding that. Through advances in computation power we can achieve
today in months what took decades in the past and there is much
research directed at these kinds of new antennas. Eventually
everyone will be able to choose and model his own antenna based on the
characteristics one wants, but without the cumbersome dimensions,
without significant bandwith limitations, without major efficiency
compromises. I believe the tradeoff (for it has to exist one) will be
ease of manufacturing.

Incidentally these new antennas have a lot to do with what Art
defines as equilibrium although I don't think he has a clear enough
definition. But it's all related to patterns, patterns which can be
found everywhere in nature an which can be expressed almost entirely
through matemathical formulas. Scaling of antennas is clearly
possible, despite of what the Chu-Harrington limit states ( or to be
fair, by applying them in a new way ).
I eagerly await the day when the 80 meter dipole will be replace by a
small device the size of a shoe box ( although it might be a bit
larger in the beginning :) ).

Regards,
Robert

Antenna physical size

On Mar 31, 5:47 pm, "Mike Kaliski" wrote:
"Richard Clark" wrote in message

...

On Mon, 31 Mar 2008 14:11:00 -0700 (PDT), wrote:

Eventually
everyone will be able to choose and model his own antenna based on the
characteristics one wants, but without the cumbersome dimensions,
without significant bandwith limitations, without major efficiency
compromises.

Hi Robert,

50 years ago they said Electricity would be so easy to produce they
would pay us to use it. They ignored Hiroshima and discovered
Chernobyl.

40 years ago they said DNA and genetics would allow us to design our
own babies. They ignored Thalidomide and discovered Dolly the sheep
that died before her time.

30 years ago they invented modeling software that would allow us to
create the Gaussian dipole (or whatever) and discovered every dipole
that came before it performed better.

Nearly 20 years ago Johnny Carson retired and we are still getting
jokes.

Not nearly 10 years ago with the Dow at 11658 and a budget surplus at
230 billion, the Republicans promised prosperity was around the corner
and their voters are now living in cardboard boxes with the Dow at
12176 and the national debt up 50%.

Scaling of antennas is clearly
possible, despite of what the Chu-Harrington limit states ( or to be
fair, by applying them in a new way ).

But you don't know how, and have never seen one either.

73's
Richard Clark, KB7QHC

Hi Richard,

I have a pair of computer speakers sitting on my desk that completely out
perform the so called ultimate hi-fi floor mounted tower system speakers I
bought 35 years ago for the equivalent of several thousand dollars in
today's money. The old speakers still work just fine but the audio experts
have learned how to squeeze that performance out of a speaker that old audio
theory predicted couldn't possibly work. Just how does a 3 inch speaker in a
cabinet the size of a couple of books manage to produce notes from 20 Hz -
20 kHz? To be fair, the small speakers can't fill a room with sound in the
same smooth way that a larger speaker cabinet can, but for everyday use in a
small modern house or apartment they are more than adequate for the majority
of people.

It seems to me that Art and others are pursuing a similar path at RF. The
aim being to produce an antenna that punches out a signal from a physically
small area. It may not perform quite as well as a full size half or full
wavelength antenna, but it will work well enough for most people with small
gardens or limited real estate for an antenna farm.

Clearly there are considerable differences in dealing with sound waves and
RF but I believe that a principle has been established that it is possible
to 'simulate' the performance of a larger system using physically small
components. Art may not be the first to get there, but he seems to be having
a damn good try and someone, somewhere will eventually succeed.

Mike G0ULI

Mike,
I am already there. Regardless of the confidence I have in my own
findings
I have cinsented for a stanger in another state to test it in a way he
feels comfortable with.
I might also remind you that the antennas are Small full wave antennas
which vastly different
to electrically small antennas that is often written about by many
including Chu!
As far as equilibrium goes it is adviseable to go back a few hundred
years when
scientists observed a static bubble and wove a mathematical response
to their puzzle.
Most people on this thread do not have a thorough understanding of the
masters laws
which are derived around the term equilibrium. Many were agast at the
idea of adding a time variable
to Gaussian law since the correllation between a closed boundary and
equilibrium
was to complicated for them to understand. Then there were those who
disliked the idea of static particles
being electrons and wanted me to state it was a part of an electron
that passed in a straight line thru the atmosphere.
These people will go into a state of shock if I called partices by the
name of neutrinos no less.
All because of the stance they have taken that all is known about
radiation. It was the small step
that I took that scientists have been looking for for years when they
began
to lose faith in classical physics snd the laws of Newton and turned
to address numourous new sciences
for answers.Now they may retreat and bind themselves more firmly to
the classical science and the pursuit of a universal law
which Einstein seached so hard for.
As far as 'all is known' older people hate change with a vengence and
will fight to the death against it with
the short time they have left on this earth . Fortunately the younger
generation always comes along with an
inquisitiveness that cannot be suppressed and are willing to rebuild
where past structures disappear below the sands.
Small FULL WAVE radiators are here now where a single element can
supply the same gain as a planar array.
Single elements that can be made with two degrees of freedom that can
also be stacked to add an extra
degree of freedom for the smallest WiFi device. I now await the
standard comments that comes along after each of my patents,
I new that already! It is really not all that special! It was me who
gave you the idea in the first place.
Anybody can get a patent ! That was already known and invented before.
It is not my fault that people didn't make it earlier!
What use is it? We already have good antennas!
Yup. Small full wave antennas are now here that can cover all
frequencies, not just all bands!
Moxon was just a tad to late to see the new antennas for small gardens
in the U.K.
Best regards
Art Unwin KB9MZ....xg (uk)