wrote:
David G. Nagel wrote:
wrote:
David G. Nagel wrote:

The last time that I built an antenna I used the formula to get the
appropriate length then I had to adjust it to obtain the optimal
readings for the frequency I was using.
Did "the formula" take into account any insulation, conductor resistivity,
conductor diameter, height above ground, characteristics of the ground,
and objects in the near field including supports?

If not, what is your point?


The point is that those items are not part of "Antenna Theory: The
Science" but are a large part of "Antenna theory: The Art". Art has been
talking as if they are one and the same.

Science is fully accounting for all variables and their effects giving
you exact answers.

Art is experience and rules of thumb that get you close enough.

As I understand it, science is trying ideas out to see what happens in
the real world. That would involve "experience" to a certain degree, as
an "educated guess" is involved in the design of the experiment.

J. B. Wood wrote:

...
Hello, Roy and all. While I aggree with the above I think one has to keep
in mind that 50 years ago there weren't software MoM (e.g. NEC) and FDTD
tools around to implement calculations that don't lend themselves to
pencil-and-paper calculation. As a result back then there was
considerable "art" (I would call it engineering) involved in antenna
design. Hams, too, were coming up with many practical designs back then
as well as now. Practical experience was important then and still is.
...
John Wood (Code 5550) e-mail:
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

Your points are well taken here.

However, I do believe there is a lot of "art" involved. We don't even
know what our signals are really composed of. We don't even really know
how propagation and movement of our signals takes place though the
medium which transports them; And, indeed, we don't even know the
medium through which they travel ... if not for brilliant and "artful"
men, this never would have occurred.

If this all does not make men stand in awe and wonder of these artistic
accomplishment and beauty of engineering achievements, I just don't know
what would!

Our imaginations have allowed us to reach out and use powers far beyond
the horizons of our vision. Sometime in the future, we will even refine
all of this ... as our vision(s) become clearer.

Warm regards,
JS

On Nov 18, 11:05*am, John Smith wrote:
J. B. Wood wrote:
...
Hello, Roy and all. *While I aggree with the above I think one has to keep
in mind that 50 years ago there weren't software MoM (e.g. NEC) and FDTD
tools around to implement calculations that don't lend themselves to
pencil-and-paper calculation. *As a result back then there was
considerable "art" (I would call it engineering) involved in antenna
design. *Hams, too, were coming up with many practical designs back then
as well as now. *Practical experience was important then and still is..
...
John Wood (Code 5550) * * * *e-mail: * * * * * * * * * *
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337

Your points are well taken here.

However, I do believe there is a lot of "art" involved. *We don't even
know what our signals are really composed of. *We don't even really know
how propagation and movement of our signals takes place though the
medium which transports them; *And, indeed, we don't even know the
medium through which they travel ... if not for brilliant and "artful"
men, this never would have occurred.

If this all does not make men stand in awe and wonder of these artistic
accomplishment and beauty of engineering achievements, I just don't know
what would!

Our imaginations have allowed us to reach out and use powers far beyond
the horizons of our vision. *Sometime in the future, we will even refine
all of this ... as our vision(s) become clearer.

Warm regards,
JS

Science is the use of known laws to determine fault or to pursue a
predefined result.
Art is to follow intuitive ideas in the hope of producing an
acceptable result

Art Unwin wrote:

...
Science is the use of known laws to determine fault or to pursue a
predefined result.
Art is to follow intuitive ideas in the hope of producing an
acceptable result

Point well taken ... Einstein seemed to have a real "art" of predicting
which areas would bear fruit, and a path to follow to deduce their inner
workings.

Regards,
JS

Dave wrote:
wrote:
David G. Nagel wrote:
wrote:
David G. Nagel wrote:

The last time that I built an antenna I used the formula to get the
appropriate length then I had to adjust it to obtain the optimal
readings for the frequency I was using.
Did "the formula" take into account any insulation, conductor
resistivity,
conductor diameter, height above ground, characteristics of the ground,
and objects in the near field including supports?

If not, what is your point?

The point is that those items are not part of "Antenna Theory: The
Science" but are a large part of "Antenna theory: The Art". Art has
been talking as if they are one and the same.

Science is fully accounting for all variables and their effects giving
you exact answers.

Art is experience and rules of thumb that get you close enough.

As I understand it, science is trying ideas out to see what happens in
the real world. That would involve "experience" to a certain degree, as
an "educated guess" is involved in the design of the experiment.

And one could say the "design of the experiment" could be an art.

Roy Lewallen wrote:

What a lot of people call the "art" of antenna design is just a
substitute for understanding. If you don't understand the underlying
science or how to apply it, the only tool you have is Kentucky windage
and guesswork, often called "art" as opposed to real understanding.
While people can very often arrive at a usable solution by using nearly
all "art" and little "science", they have more and better solutions to
choose from as they replace some of that "art" with "science".


What I have found is that the antennas I design tend to mirror the
software. The times they have not, I can usually look around and find
the thing that causes it, maybe the height I ended up at wasn't the one
used for the design, maybe a metal structure, ground characteristics
were not the same. etc.

I think we attribute to "art" that which we do not know at the time. As
we know more, it all turns into science.

- 73 de Mike N3LI -

On Sun, 16 Nov 2008 23:30:08 GMT, "Dave" wrote:


"JIMMIE" wrote in message
...
Isnt this all a little bit like acknowleging someone who is causing
intentional interference on the bands?

yeah, but not like someone who is nasty, more like someone who is funny and
keeps blabbering on saying more and more ridiculous things.


Still QRN is QRN. I just do not enjoy noise as well as i enjoy the
desired signals.

On Sun, 16 Nov 2008 21:44:07 +0000, Dave wrote:

Richard Harrison wrote:
Dave wrote:
"High power coaxial transmission lines have hollow center conductors."

Yes, and the metal which could have filled the hollow space would add no
conductivity at HF.

Best regards, Richard Harrison, KB5WZI


Power handling and efficiency increase as the frequency decreases; a
solid center conductor doesn't help at LF either.

http://www.myat.com/index.html


As a matter of fact skin depth tends to keep power conductors (50/60
Hz) below 1 inch (25 mm) diameter. It becomes easier and cheaper to
"quad them up" (four conductors a couple of hand spans apart).

On Sun, 16 Nov 2008 15:14:23 -0600, (Richard
Harrison) wrote:

Art wrote:
"Einstein may well have been correct even tho not aware of discovries
found after his death."

Wouldn`t anyone like to be aware of all the discoveries made before his
death?

Einstein said something like: "Keep it simple, but not too simple!"

Scientists have in many instances followed Einstein`s advice and reduced
things to simplest terms. Maxwell`s equations as simplified and
explained by Heaviside have been used to successfully predict EM
behavior for a century.

Just to be picky, Heaviside predates Einstein:

http://en.wikipedia.org/wiki/Oliver_Heaviside

They give the answers needed so there has been
no great search for a replacement.

The research at CERN on colliding beams is more likely of interest to
those working with ionizing radiation than to those working with the
nonionizing type we use in radio telecommunications.

There is and was agreement among many with Kraus when he wrote on page
37 of the 3rd edition of "Antennas":
"Although a charge moving with uniform velocity along a straight
conductor does not radiate, a charge moving back and forth in simple
harmonic motion along the conductor is subject to acceleration (and
deceleration) and radiates."

An interesting view of the mechanism of radiation is given by B.
Whitfield Griffith, Jr. on page 315 of "Radio-Electronic Transmission
Fundamentals".

Best regards, Richard Harrison, KB5WZI